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Journal Articles

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2020

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• Bordoy J, Schott D J, Xie J, Bannoura A, Klein P, Striet L, Hoeflinger F, Haering I, Reindl L M, Schindelhauer C
  Acoustic Indoor Localization Augmentation by Self-Calibration and Machine Learning
  2020 MDPI Sensors, volume: 20, issue: 4
• Laufer B, Murray R, Docherty P D, Krüger-Ziolek S, Höflinger F, Reindl L, Möller K
  Anzahl und Position von Sensoren in einem Smart-Shirt zur Bestimmung von Tidalvolumina
  2020 Proceedings on Automation in Medical Engineering, volume: 1, issue: 1, pages: 018 - 018
• Stoecklin S, and Yousaf A, Gidion G, Reindl L
  Efficient Wireless Power Transfer With Capacitively Segmented RF Coils
  2020 IEEE Access, volume: 8, pages: 24397 - 24415
• Bordoy J, Schindelhauer C, Höflinger F, Reindl L M
  Exploiting Acoustic Echoes for Smartphone Localization and Microphone Self-Calibration
  2020 IEEE T Instrum Meas, volume: 69, issue: 4, pages: 1484 - 1492
• G. H. Ibrahim, U. Zschieschang, H. Klauk, L. M. Reindl
  High-Frequency Rectifiers Based on Organic Thin-Film Transistors on Flexible Substrates
  2020 IEEE Trans. Electron Devices, volume: 67, issue: 6, pages: 2365 - 2371
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  Abstract

  Rectifier circuits featuring low threshold voltages and high cutoff frequencies based on p-channel organic thin-film transistors (TFTs) have been designed, fabricated and characterized. The TFTs and circuits were fabricated by shadow-mask lithography on flexible plastic substrates using the vacuum-deposited small-molecule organic semiconductor dinaphtho[2,3-b: 2′ , 3′ -f]thieno[3,2-b] thiophene (DNTT). The TFTs have a gate dielectric with a thickness of 5.3 nm and a channel length of 10 μm . The study considers the frequency characteristics of diode-connected transistors (transdiodes) and adopts circuit techniques from silicon CMOS technology, namely single-stage and multistage dynamic-threshold-compensated differential rectifiers. The characterization of the rectifier circuits indicates cutoff frequencies up to 4.75 MHz at a peak-to-peak input voltage of 3 V for transdiodes, up to 32 MHz at a peak-to-peak input voltage of 1.5 V for single-stage differential rectifiers and up to 7.5 MHz at a peak-to-peak input voltage of 1.5 V for two-stage rectifiers. The efficiency is 25% for a load of 10 MΩ and below 1% for a load of 1 MΩ.
• Ibrahim GH, Zschieschang U, Klauk H, Reindl LM
  High-Frequency Rectifiers Based on Organic Thin-Film Transistors on Flexible Substrates
  2020 IEEE T Electron Dev, volume: 67, issue: 6, pages: 2365 - 2371
• Laufer B, Docherty P D, Krüger-Ziolek S, Höflinger F, Reindl L, Möller K
  Methode zur Bestimmung atembasierter Umfangsänderungen
  2020 Proceedings on Automation in Medical Engineering, volume: 1, issue: 1, pages: 015 - 015

2019

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• Karacocuk G, Höflinger F, Zhang R, Reindl L M, Laufer B, Möller K, Röell M, Zdzieblik D
  Inertial Sensor-Based Respiration Analysis
  2019 IEEE T Instrum Meas, volume: 68, issue: 11, pages: 4268 - 4275
• Krampert D, Unsleber S, Janssen C, Reindl L
  Load Measurement in Linear Guides for Machine Tools
  2019 MDPI Sensors, volume: 19, issue: 15, page: 3411

2018

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• Bhattacharyya M, Gruenwald W, Jansen D, Reindl L, Aghassi-Hagmann J
  An Ultra-Low-Power RFID/NFC Frontend IC Using 0.18 $\mu$m CMOS Technology for Passive Tag Applications
  2018 MDPI Sensors, volume: 18, issue: 5, page: 1452
• Bhattacharyya M, Gruenwald W, Jansen D, Reindl L, Aghassi-Hagmann J
  Design of a programmable passive SoC for biomedical applications using RFID ISO 15693/NFC5 interface
  2018 Journal of Low Power Electronics and Applications, volume: 8, issue: 4, page: 3
• Khan FA, Yousaf A, Reindl LM
  Dual Segment Glocal Model Based Capacitive Level Sensor (CLS) for Adhesive Material and Level Detection
  2018 Frequenz, volume: 72, pages: 261 - 266
• Gruenwald W, Bhattacharrya M, Jansen D, Reindl L
  Electromagnetic Analysis, Characterization and Discussion of Inductive Transmission Parameters for Titanium Based Housing Materials in Active Medical Implantable Devices
  2018 MDPI Materials, volume: 11, issue: 11, page: 2089
• Laufer, Bernhard, Krueger-Ziolek, Sabine, Moeller, Knut, Docherty, Paul David, Hoeflinger, Fabian, Reindl, Leonhard
  Hierarchical Analysis of Thorax Models to Measure Tidal Volume
  2018 Current Directions in Biomedical Engineering, volume: 4, issue: 1, pages: 429 - 432
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  Abstract

  Motion tracking of thorax kinematics can be used to determine respiration. However, determining a minimal sensor configuration from 64 candidate sensor locations is associated with high computational costs. Hence, a hierarchical optimization method was proposed to determine the optimal combination of sensors. The hierarchical method was assessed by its ability to quickly determine the sensor combination that will yield optimal modelled tidal volume compared to body plethysmograph measurements. This method was able to find the optimal sensor combinations, in approximately 2% of the estimated time required by an exhaustive search.
  
  
   
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• Laufer B, Krueger-Ziolek S, Moeller K, David Docherty P, Höflinger F, Reindl L
  Hierarchical Analysis of Thorax Models to Measure Tidal Volume
  2018 Current Directions in Biomedical Engineering, volume: 4, issue: 1, pages: 429 - 432
• J. Kokert, T. Beckedahl, L. M. Reindl
  Medlay: A Reconfigurable Micro-Power Management to Investigate Self-Powered Systems
  2018 Sensors, volume: 18, issue: 1, page: 259
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  Abstract

  In self-powered microsystems, a power management is essential to extract, transfer and regulate power from energy harvesting sources to loads such as sensors. The challenge is to consider all of the different structures and components available and build the optimal power management on a microscale. The purpose of this paper is to streamline the design process by creating a novel reconfigurable testbed called Medlay. First, we propose a uniform interface for management functions e.g., power conversion, energy storing and power routing. This interface results in a clear layout because power and status pins are strictly separated, and inputs and outputs have fixed positions. Medlay is the ready-to-use and open-hardware platform based on the interface. It consists of a base board and small modules incorporating e.g., dc-dc converters, power switches and supercapacitors. Measurements confirm that Medlay represents a system on one circuit board, as parasitic effects of the interconnections are negligible. The versatility regarding different setups on the testbed is determined to over 250,000 combinations by layout graph grammar. Lastly, we underline the applicability by recreating three state-of-the-art systems with the testbed. In conclusion, Medlay facilitates building and testing power management in a very compact, clear and extensible fashion.
• Kokert J, Beckedahl T, Reindl L
  Medlay: A reconfigurable micro-power management to investigate self-powered systems
  2018 MDPI Sensors, volume: 18, issue: 1, page: 259
• Laufer B, Krueger-Ziolek S, Docherty P D, Höflinger F, Reindl L, Moeller K
  Minimum Number of Sensors in a Smart Shirt to Measure Tidal Volumes
  2018 IFAC-PapersOnLine, volume: 51, issue: 27, pages: 92 - 97

2017

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• R. Zhang, H. Yang, F. Höflinger, L.M. Reindl
  Adaptive Zero Velocity Update Based on Velocity Classification for Pedestrian Tracking
  2017 IEEE Sensors Journal, volume: 17, issue: 7, pages: 2137 - 2145
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  Abstract

  Due to the drift of low-cost micro-electro-mechanical systems sensors and recursive computation, pedestrian tracking based on foot-mounted inertial sensors suffers from accumulative velocity and position errors. The well-known approach named zero velocity update (ZUPT) is able to minimize such errors by resetting the velocity to zero when the foot does not move with respect to ground. This time duration is called the still phase of a stride and can be detected by comparing the actual sensor data with a pre-defined threshold. However, when the velocity increases or decreases, the fixed threshold may be too small or too big for the correct detection of the still phase. Based on our previous study, this paper presents a novel adaptive ZUPT approach using an additional chest-attached accelerometer for consistent removal of accumulative errors even if the velocity changes. The information extracted from the chest acceleration is used to update corresponding threshold for the still-phase detection, and, hence, to determine error-free velocity and position information. The experimental results show that the accurate tracking trajectory can still be successfully obtained even if the velocity changes rapidly during the experiment.
• S. Gopisetty, P. Treffinger, L. M. Reindl
  Open-source energy planning tool with easy-to-parameterize components for the conception of polygeneration systems
  2017 Energy, volume: 126, pages: 756 - 765
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  Abstract

  Polygeneration systems are a key technology for the reduction of primary energy usage and emissions. High costs, lack of flexibility and effort for parameterization hinder the wide usage of modeling tools during their conceptual design. This paper describes how planning tools can be structured for the conceptual design phase where only little information is available to the planner. A library concept was developed using the principles of object-oriented modeling to address the flexibility issue. With respect to cost and expandability, the open-source modeling language Modelica was chosen. Furthermore, easyto- parameterize component models were developed. In addition to the improved library concept and novel component models, an easy-to-adapt control concept is proposed. The component models were validated and the applicability of the library was demonstrated by means of an example. It was shown that the data usually obtained from spec sheets are sufficient to parameterize the models. In addition to this, the control concept was approved.
• T. Kumberg, M. Schink, L.M. Reindl, C. Schindelhauer
  T-ROME: A simple and energy efficient tree routing protocol for low-power wake-up receivers
  2017 Ad Hoc Netw, volume: 59, pages: 97 - 115
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  Abstract

  Wireless sensor networks are deployed in many monitoring applications but still suffer from short life- times originating from limited energy sources and storages. Due to their low-power consumption and their on-demand communication ability, wake-up receivers represent an energy efficient and simple en- hancement to wireless sensor nodes and wireless sensor network protocols. In this context, wake-up receivers have the ability to increase the network lifetime. In this article, we present T-ROME, a simple and energy efficient cross-layer routing protocol for wireless sensor nodes containing wake-up receivers. The protocol makes use of the different transmission ranges of wake-up and main radios in order to save energy by skipping nodes during data transfer. With respect to energy consumption and latency, T-ROME outperforms existing protocols in many scenarios. Here, we describe and analyze the cross layer multi-hop protocol by means of a Markov chain model that we verify using a laboratory test setup.

2016

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• A. Bannoura, F. Höflinger, O. Gorgies, G.U. Gamm, J. Albesa, L.M. Reindl
  Acoustic Wake-Up Receivers for Home Automation Control Applications
  2016 Electronics -Journal, volume: 5, issue: 1, 4
• J. Bordoy, A. Traub-Ens, A. Sadr, J. Wendeberg, F. Höflinger, C. Schindelhauer, L. M. Reindl
  Bank of Kalman Filters in Closed-Loop for Robust Localization Using Unsynchronized Beacons
  2016 IEEE SENSORS JOURNAL, volume: 16, issue: 22
• M. Erd, F. Schaeffer, M. Kostic, L. M. Reindl
  Event monitoring in emergency scenarios using energy efficient wireless sensor nodes for the disaster information management
  2016 International Journal of Disaster Risk Reduction, volume: 16, pages: 33 - 42
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  Abstract

  Information gathering in tunnels, buildings, bridges, etc. during disasters is of vital importance in speeding up rescue efforts and for protecting the fire fighters. The collected data can be used by the emergency services in the planning of rescue operations and allocation of human resources at a local level. In this article we present design and implementation of a wireless sensor network, which consists of energy-efficient wireless sensor nodes with an integrated ultrasonic sensor, which establish a collision free data transmission in an emergency scenario. The developed network was tested in a field experiment in an explosion within a building to confirm its functionality and reliability. The wireless sensor network was able to pass critical data to the emergency units to initiate the rescue procedures during this disaster scenario.
• H. Yang, R. Zhang, J. Bordoy, F. Höflinger, W. Li, C. Schindelhauer, L. M. Reindl
  Smartphone based integrated Indoor Localization System using Inertial Sensor and Acoustic Transmitter/Receiver
  2016 IEEE SENSORS JOURNAL, volume: 16, issue: 22
• B. Stegemann, K. M. Gad, P. Balamou, D. Sixtensson, D. Vössing, M. Kasemann, H. Angermann
  Ultra-thin silicon oxide layers on crystalline silicon wafers: Comparison of advanced oxidation techniques with respect to chemically abrupt SiO2/Si interfaces with low defect densities
  2016 Appl. Surf. Sci.
• K. M. Gad, D. Vössing, A. Richter, B. Rayner, L. M. Reindl, S. E. Mohney, M. Kasemann
  Ultrathin Titanium Dioxide Nanolayers by Atomic Layer Deposition for Surface Passivation of Crystalline Silicon
  2016 IEEE J. Photovoltaics, volume: 6, issue: 3, pages: 1 - 5

2015

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• M. Knapp, A. M. Lomonosov, P. Warkentin, P. M. Jäger, W. Ruile, H.-P. Kirschner, M. Honal, I. Bleyl, A. P. Mayer, L. M. Reindl
  Accurate characterization of SiO2 thin films using surface acoustic waves
  2015 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, volume: 62, issue: 3, pages: 736 - 743
• A. Ens, F. Höflinger, J. Wendeberg, J. Hoppe, R. Zhang, A. Bannoura, L.M. Reindl, C. Schindelhauer
  Acoustic Self-Calibrating System for Indoor Smart Phone Tracking
  2015 International Journal of Navigation and Observation, volume: 2015
• A. Nimo, T. Beckedahl, T. Ostertag, L. Reindl
  Analysis of Passive RF-DC Power Rectification and Harvesting Wireless RF Energy for Micro-watt Sensors
  2015 AIMS Energy, volume: 3, issue: 2, pages: 184 - 200
• M. Schulz, E. Mayer, I. Shrena, D. Eisele, M. Schmitt, L. M. Reindl, H. Fritze1
  Correlation of BAW and SAW properties of langasite at elevated temperatures
  2015 Journal of Sensors and Sensor Systems, volume: 4, pages: 331 - 340
• A. Traub-Ens, J. Bordoy, J. Wendeberg, L. M. Reindl, C. Schindelhauer
  Data Fusion of Time Stamps and Transmitted Data for unsynchronized Beacons
  2015 IEEE Sensors Journal, volume: 15, issue: 10, pages: 5042 - 5049
• S. Stöcklin, A. Yousaf, T. Volk, L.M. Reindl,
  Efficient Wireless Powering of Biomedical Sensor Systems for Multichannel Brain Implants
  2015 IEEE Transactions on Instrumentation and measurement, issue: 99, pages: 1 - 11
• J.-M. Boccard, T. Aftab, J. Hoppe, A. Yousaf, R. Huetter, L.M. Reindl
  High-Resolution, Far-field and Passive Temperature Sensing up to 700°C using an Isolated ZST Microwave Dielectric Resonator
  2015 IEEE Sensors Journal, volume: 2015, issue: 99, page: 1
• K. M. Gad, D. Vössing, P. Balamou, D. Hiller, B. Stegemann, H. Angermann, M. Kasemann
  Improved Si/SiOx interface passivation by ultra-thin tunneling oxide layers prepared by rapid thermal oxidation
  2015 Appl. Surf. Sci., volume: 353, pages: 1269 - 1276
• A. Ens, L. M. Reindl
  Mehrträger-Ultraschall-Kommunikation für die Innenraum-Lokalisierung
  2015 tm - Technisches Messen, volume: 82, issue: 3, pages: 117 - 126
• A. Ens, L. M. Reindl
  Multicarrier Airborne Ultrasound Transmission With Piezoelectric Transducers
  2015 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, volume: 62, issue: 5, pages: 905 - 914
• A. Ens, L. M. Reindl
  Piezoelectric transceiver matching for multiple frequencies
  2015 Journal of Sensors and Sensor Systems, volume: 4, pages: 9 - 16
• Heinrich M, Kraft A, Lieder M, Hoex B, Aberle AG, Glatthaar M
  Quantification of Front Side Metallization Area on Silicon Wafer Solar Cells for Background Plating Detection
  2015 Energy Procedia, volume: 77, pages: 717 - 724
• T. Volk, S. Gorbey, M. Bhattacharyya, W. Grünwald, T. Stieglitz, L. Reindl, B. Lemmer, D. Jansen
  RFID Technology for Continuous Monitoring of Physiological Signals in Small Animals
  2015 IEEE Transactions on Biomedical Engineering, volume: 62, issue: 2
  
   
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• T. Volk, S. Gorbey, W. Grünwald, M. Bhattacharyya, L. Reindl, B. Lemmer, D. Jansen
  Semi-passive powered biotelemetry for small animals
  2015 Sensors and Actuators A: Physical, volume: 221, pages: 95 - 103
• A. Bannoura, C. Ortolf, L. Reindl, C. Schindelhauer
  The Wake Up Dominating Set Problem
  2015 Theoratical Computer Science, pages: 1 - 16
• T. Janson, A. Traub-Ens, C. Schindelhauer, L.M. Reindl
  Turning Interferences into Noise in Ad Hoc Networks
  2015 Telecommunication Systems, Springer US, volume: 60, issue: 1, pages: 243 - 254

2014

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• Fischer S., Fröhlich B., Steinkemper H., Krämer K.W., Goldschmidt J.C.
  Absolute upconversion quantum yield of β-NaYF₄ doped with Er3+ and external quantum efficiency of upconverter solar cell devices under broad-band excitation considering spectral mismatch corrections
  2014 Sol Energ Mat Sol C, volume: 122, pages: 197 - 207
• Heinrich, M, Kluska, S, Binder, S, Hameiri, Z, Hoex, B, Aberle, AG
  Accurate potential drop sheet resistance measurements of laser-doped areas in semiconductors
  2014 Journal of Applied Physics, volume: 116, issue: 13, page: 134505
• Breitwieser, Matthias, Heinz, Friedemann D., Büchler, Andreas, Kasemann, Martin, Schön, Jonas, Warta, Wilhelm, Schubert, Martin C.
  Analysis of solar cell cross sections with micro-light beam induced current (µLBIC)
  2014 Solar Energy Materials and Solar Cells
• Rüdiger M., Fischer S., Frank J., Ivaturi A., Richards B.S., Krämer K.W., Hermle M., Goldschmidt J.C.
  Bifacial n-type silicon solar cells for upconversion applications
  2014 Sol Energ Mat Sol C, volume: 128, pages: 57 - 68
• R. Zhang, F. Höflinger, L. M. Reindl
  Calibration of an IMU using 3D Rotation Platform
  2014 IEEE Sensors Journal Sensors Journal, volume: 14, issue: 06, pages: 1778 - 1787
• Q. Hamp, L. Reindl, D. Güthlin
  Decision-making behaviour during urban search and rescue: a case study of Germany
  2014 Disasters, volume: 38, issue: 1, pages: 84 - 107
• Arnaoutakis G.E., Marques-Hueso J., Ivaturi A., Krämer K.W., Fischer S., Goldschmidt J.C., Richards B.S.
  Enhanced up-conversion for photovoltaics via concentrating integrated optics
  2014 Opt Express, volume: 22, pages: A452 - A464
• T. Volk, M. Bhattacharyya, W. Grünwald, L. Reindl, D. Jansen
  Formal Description of Inductive Air Interfaces Using Thévenin’s Theorem and Numerical Analysis
  2014 IEEE transactions on magnetics, volume: 50, issue: 6, pages: 1 - 9
• A. Büchler, S. Kluska, M. Kasemann, M. Breitwieser, W. Kwapil, A. Hähnel, H. Blumtritt, S. Hopman, M. Glatthaar
  Localization and characterization of annealing-induced shunts in Ni-plated monocrystalline silicon solar cells
  2014 Phys Status Solidi-r, volume: 5, pages: 385 - 389
• R. Zeiser, S. Ayub, J. Hempel, M. Berndt, J. Wilde
  Mechanical Stress Analyses of Packaged Pressure Sensors for Very High Temperatures
  2014 Journal of Microelectronics and Electronic Packaging, volume: 11, issue: 1, pages: 30 - 36
• J. Oller, I. Demirkol, J. Casademont, J. Paradells, G. U. Gamm, L. Reindl
  Performance Evaluation and Comparative Analysis of SubCarrier Modulation Wake-up Radio Systems for Energy-Efficient Wireless Sensor Networks
  2014 Sensors, volume: 14, issue: 1, pages: 22 - 51
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  Abstract

  Energy-efficient communication is one of the main concerns of wireless sensor networks nowadays. A commonly employed approach for achieving energy efficiency has been the use of duty-cycled operation of the radio, where the node’s transceiver is turned off and on regularly, listening to the radio channel for possible incoming communication during its on-state. Nonetheless, such a paradigm performs poorly for scenarios of low or bursty traffic because of unnecessary activations of the radio transceiver. As an alternative technology, Wake-up Radio (WuR) systems present a promising energy-efficient network operation, where target devices are only activated in an on-demand fashion by means of a special radio signal and a WuR receiver. In this paper, we analyze a novel wake-up radio approach that integrates both data communication and wake-up functionalities into one platform, providing a reconfigurable radio operation. Through physical experiments, we characterize the delay, current consumption and overall operational range performance of this approach under different transmit power levels. We also present an actual single-hop WuR application scenario, as well as demonstrate the first true multi-hop capabilities of a WuR platform and simulate its performance in a multi-hop scenario. Finally, by thorough qualitative comparisons to the most relevant WuR proposals in the literature, we state that the proposed WuR system stands out as a strong candidate for any application requiring energy-efficient wireless sensor node communications.
• Breitwieser, Matthias, Heinz, Friedemann D., Rachow, Thomas, Kasemann, Martin, Janz, Stefan, Warta, Wilhelm, Schubert, Martin C.
  Process Control and Defect Analysis for Crystalline Silicon Thin Films for Photovoltaic Applications by the Means of Electrical and Spectroscopic Microcharacterization Tools
  2014 IEEE Journal of Photovoltaics, volume: 4, pages: 1275 - 1281
• J. Hempel, S. Anees, E. Zukowski, M. Berndt, J. Wilde, L. Reindl
  STRAIN TRANSFER ANALYSIS OF INTEGRATED SURFACE ACOUSTIC WAVE SENSORS
  2014 Journal of Electronic Packaging
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  Abstract

  This paper presents a strain transfer investigation for Surface Acoustic Wave (SAW) strain sensors. For evaluation, a SAW strain sensor is assembled with a pre-tested bond material for potentially high strain transfer on a test holder. The setup is stressed with an axially homogeneous strain up to 500 ppm. The strain transfer ratio is computed from the applied load, the reference measurements with foil strain gauge, and the measured SAW strain sensor signal. The strain transfer performance of the bond material is also investigated with respect to the temperature dependency in the range between 22 °C and 85 °C. At this elevated temperatures an average strain transfer ratio of 0.606 ± 0.7% was measured. Mechanical load cycling tests up to 1000 cycles are used for the evaluation of the elastic fatigue of the bond material. The effects of mechanical load cycling and aging of the bond layer are analyzed with the SAW strain sensor response. After 1000 mechanical load cycles the transferred strain into the SAW strain sensor is 0.582 ± 0.153%. Finally, the experimental results are compared with the results of a 3D FEM simulation which are deviating less than 10%.
• K. Retan, A. Graf, L. Reindl
  Simulative verification of a novel semi-active broadband energy harvester
  2014 Joural of Sensors and Sensor Systems, volume: 3, pages: 21 - 28
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  Abstract

  This paper presents a semi-active broadband vibrational-energy harvesting system. Based on a non-resonant rotational generator, electronic circuitry was used to overcome the physical start-up restrictions. Due to the functional design it remains an energy harvester suitable for battery-less devices. For the first time a vibrational energy harvester is presented that allows standardization and thus higher volume production. A system layout, simulation, and measurement data will be shown.
• Hannes Höffler, Hasan Al-Mohtaseb, Nico Wöhrle, Bernhard Michl, Martin Kasemann, JonasHaunschild
  Spatially Resolved Determination of Junction Voltage of Silicon Solar Cells
  2014 Energy Procedia, volume: 55, pages: 85 - 93
• Fischer S., Martín-Rodríguez R., Fröhlich B., Krämer K.W., Meijerink A., Goldschmidt J.C.
  Upconversion Quantum Yield of Er3+-doped β-NaYF₄ and Gd2O2S: The effects of host lattice, Er3+ doping, and excitation spectrum bandwidth
  2014 J Lumin, volume: 153, pages: 281 - 287
• Fischer S., Ivaturi A., Fröhlich B., Rüdiger M., Richter A., Krämer K.W., Richards B.S., Goldschmidt J.C.
  Upconverter Silicon Solar Cell Devices for Efficient Utilization of Sub-Band-Gap Photons Under Concentrated Solar Radiation
  2014 IEEE Journal of Photovoltaics, volume: 4, pages: 183 - 189
• Höffler, Hannes, Al-Mohtaseb, Hasan, Haunschild, Jonas, Michl, Bernhard, Kasemann, Martin
  Voltage calibration of luminescence images of silicon solar cells
  2014 Journal of Applied Physics, volume: 115, page: 034508

2013

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• F. Höflinger, R. Zhang, L.M. Reindl, J. Müller, W. Burgard
  A wireless micro inertial measurement unit (WIMU)
  2013 IEEE Transactions on Instrumentation & Measurement, volume: 62, issue: 8, pages: 2583 - 2595
• J. Wendeberg, F. Höflinger, Ch. Schindelhauer, L. Reindl
  Calibration-free TDOA Self-Localization
  2013 Journal of Location Based Services
• M. Schmitt, K. Schmidt, S. Olfert, J. Rautenberg, G. Lindner, B. Henning, L. M. Reindl
  Detection of coatings within liquid-filled tubes and containers by mode conversion of leaky Lamb waves
  2013 Journal of Sensors and Sensor Systems, volume: 2, pages: 73 - 84
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  Abstract

  In this paper, a new acoustic sensor principle for coating detection within liquid-filled tubes and containers based on mode conversion of leaky Lamb waves is introduced. Leaky Lamb waves are excited and detected by single-phase transducers, which are attached on the outer side of a tube or container. By transmission time and amplitude measurements, coating formation within the liquid-filled tube and container is detected non-invasively. This new sensor principle is subdivided into the separate considerations of Lamb wave excitation, mode conversion and inverse mode conversion. The Lamb wave excitation by a single-phase transducer is visualized by scanning laser Doppler vibrometer imaging. The mode conversion process of leaky Lamb waves is measured by membrane hydrophone measurements and Schlieren visualization; afterwards, the measured emission angles are compared with the theoretical one. The inverse mode conversion process of pressure waves back to leaky Lamb waves is visualized by Schlieren images. By merging the results of Lamb wave excitation, mode conversion and inverse mode conversion, the new sensor concept is explained. Theoretical considerations and measurement results of adhesive tape coating inside a liquid-filled plastic tube and a liquid-filled stainless steel container verify the new acoustic sensor principle. Finally the measuring sensitivity and the technical realization are discussed.
• J. Bardong, T. Aubert, N. Naumenko, G. Bruckner, S. Salzmann, L. M. Reindl
  Experimental and theoretical investigations of some useful langasite cuts for high-temperature SAW applications
  2013 IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, volume: 60, issue: 4, pages: 814 - 823
• Heinrich, M, Kluska, S, Hameiri, Z, Hoex, B, Aberle, AG
  Extracting physical properties of arbitrarily shaped laser-doped micro-scale areas in semiconductors
  2013 Applied Physics Letters, volume: 103, issue: 26, page: 262103
• I. Shrena, D. Eisele, J. Bardong, E.Mayer, L. Reindl
  High Precision Signal Processing Algorithm to Evaluate SAW Properties as a Function of Temperature
  2013 IEEE Trans. Ultrason. Ferroelectr. Freq. Control, volume: 60, issue: 4, pages: 805 - 813
• Martín-Rodríguez R., Fischer S., Avaturi I., Fröhlich B., Krämer K.W., Goldschmidt J.C., Richards B.S., Meijerink A.
  Highly Efficient IR to NIR Upconversion in Gd2O2S: Er3+ for Photovoltaic Applications
  2013 Chem Mater, volume: 25, pages: 1912 - 1921
• M. Freunek(Müller), M. Freunek, L.M. Reindl
  Ideal and Empirical Maximum Efficiencies for Indoor Photovoltaic Devices
  2013 IEEE Journal of Photovoltaics, volume: 3, issue: 1, pages: 59 - 64
• Herter B., Wolf S., Fischer S., Gutmann J., Bläsi B., Goldschmidt J.C.
  Increased upconversion quantum yield in photonic structures due to local field enhancement and modification of the local density of states - a simulation-based analysis
  2013 Opt Express, volume: 21, pages: A883 - A900
• R. Zhang, F. Höflinger, L.M. Reindl
  Inertial Sensor Based Indoor Localization and Monitoring System for Emergency Responders
  2013 IEEE Sensors Journal, volume: 13, issue: 2, pages: 838 - 848
• J.-M. Boccard, P. Katus, R. Renevier, L. M. Reindl, J.-M. Friedt
  Near-field interrogation of SAW resonators on rotating machinery
  2013 Journal of Sensors and Sensor Systems, volume: 2, pages: 147 - 156
• A. Yousaf, J.-M. Boccard, F. A. Khan, L. M. Reindl
  Near-field wireless sensing of single and multiple open-ended micro coils
  2013 Journal of Sensors and Sensor Systems, volume: 2, pages: 35 - 43
• Fischer S., Hallermann F., Eichelkraut T., von Plessen G., Krämer K.W., Biner D., Steinkemper H., Hermle M., Goldschmidt J.C.
  Plasmon enhanced upconversion luminescence near gold nanoparticles-simulation and analysis of the interactions: Errata
  2013 Opt Express, volume: 21, pages: 10606 - 10611
• G. U. Gamm, S. Sester, L. M. Reindl
  SmartGate – connecting wireless sensor nodes to the Internet
  2013 Journal of Sensors and Sensor Systems, issue: 2, pages: 45 - 50
  » show abstract« hide abstract
  Abstract

  Wireless sensor nodes inside buildings are used to read out sensor data and to control actuators. The nodes need to operate for a long time with a single battery. Often the sensor data should be accessible via Internet from every point of the world. When using a standard Wi-Fi connection, the battery of the node would be depleted after a few hours due to idle currents in receive state. Using sensor nodes with included wake-up receivers can prolong the lifetime of the sensor network to several years. However, no gateway exists that can, on the one hand, connect itself to the Internet and on the other hand can send out the special coded wake-up signal needed by the wake-up receivers on the nodes. In this work we want to bridge this gap by introducing the SmartGate. It is a gateway that has two transceivers incorporated on a single printed circuit board (PCB). A Wi-Fi module connects itself to an existing Wi-Fi network and listens for incoming messages. A CC430 microcontroller analyzes the incoming Wi-Fi messages and builds up the corresponding wake-up signal with included 16-bit address coding. The wake-up signal is sent out using the integrated CC1101 transceiver core from Texas Instruments. A woken-up node will read out its sensor data and will transmit it back to the gateway, where it will be packed into a TCP/IP packet and sent back to the user. The use of the gateway allows the implementation of a wireless sensor network with wake-up receivers that can be accessed via Internet from every point of the world.
• Steinkemper H., Fischer S., Hermle M., Goldschmidt J.C.
  Stark level analysis of the spectral line shape of electronic transitions in rare earth ions embedded in host crystals
  2013 New J Phys, volume: 15, page: 055033
• Zhang R., Höflinger F., Reindl L. M.
  TDOA-based Localization Using Interacting Multiple Model Estimator and Ultrasonic Transmitter/Receiver
  2013 IEEE Transactions on Instrumentation & Measurement, volume: 62, issue: 8, pages: 2205 - 2214
• Liu, L, Lin, F, Heinrich, M, Aberle, AG, Hoex, B
  Unexpectedly High Etching Rate of Highly Doped n-Type Crystalline Silicon in Hydrofluoric Acid
  2013 ECS Journal of Solid State Science and Technology, volume: 2, issue: 9, pages: P380 - P383

2012

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• Q. Hamp, L.M. Reindl
  Association performance enhancement through classification
  2012 Journal of Advances in Information Fusion
• L. Chen, M. Loschonsky, L.M. Reindl
  Autoregressive Modeling of Mobile Radio Propagation Channel in Building Ruins
  2012 IEEE Transactions on Microwave Theory and Techniques, volume: 60, issue: 5, pages: 1478 - 1489
  » show abstract« hide abstract
  Abstract

  This paper addresses an autoregressive (AR) spectral estimation technique adapted for modeling of radio propagation channel in collapsed buildings and urban ruins in the frequency domain. Two mobile communication bands, 900 and 1800 MHz, were investigated. Measured channel frequency responses (CFRs)were firstly modeled by an overestimated AR model. In order to reduce this initial model order, the original CFRs were filtered and decimated. The model order was then optimized using the criteria of the signal-to-noise ratio and the maximum excess delay. According to the different debris structures, antenna polarization andRFs, the finalmodel orderwas from 3 up to 35. The normalized root mean square error of modeled CFRs was between 0.22–0.38 on average. In order to generate a channel simulator, the statistical distribution functions of the simulator parameters, such as the number, arrival time, and complex amplitude of multipath components, were computed from the AR estimated channel impulse responses. Each of these distributions corresponds to the frequency band, antenna polarization, and ruin structure as well.
• Y. Augarten, T. Trupke, M. Lenio, J. Bauer, J.W. Weber, M. Juhl, M. Kasemann, O. Breitenstein
  Calculation of quantitative shunt values using photoluminescence imaging
  2012 Prog. Photovolt: Res. Appl, page: n/a
• M. Kasemann, L.M. Reindl, B. Michl, W. Warta, A. Schütt, J. Carstensen
  Contactless Qualitive Series Resistance Imaging on Solar Cells
  2012 IEEE Journal of Photovoltaics, volume: 2, issue: 2, pages: 181 - 183
• Q. Hamp, D. Güthlin, L.M. Reindl
  Decision behavior during Urban Search and Rescue - A German Case Study
  2012 Disasters Journal
• Goldschmidt J.C., Fischer S., Steinkemper H., Hallermann F., von Plessen G., Krämer K.W., Biner D., Hermle M.
  Increasing Upconversion by Plasmon Resonance in Metal Nanoparticles-A Combined Simulation Analysis
  2012 IEEE Journal of Photovoltaics, volume: 2, pages: 134 - 140
• G.U. Gamm, M. Kostic, M. Sippel, L.M. Reindl
  Low power sensor node with addressable wake-up on demand capability
  2012 Int. J. Sensor Networks, volume: 11, issue: 1, pages: 48 - 56
• Fischer S., Steinkemper H., Löper P., Hermle M., Goldschmdit J.C.
  Modeling upconversion of erbium doped microcrystals based on experimentally determined Einstein coefficients
  2012 J Appl Phys, volume: 111, page: 013109
• J. Albesa, M. Gasulla
  Monitoring Switch-Type Sensors via Inductive Coupling: Application to Occupancy and Belt Detection in Removable Vehicle Seats
  2012 Ieee T Power Electr, volume: 27, pages: 4472 - 4480
• Q. Hamp, R. Zhang, L. Chen, O. Gorgis, T. Ostertag, M. Loschonsky, L.M. Reindl
  New technologies for the search of trapped victims
  2012 Journal of Ad Hoc Networks
• Frank J., Rüdiger M., Fischer S., Goldschmidt J.C., Hermle M.
  Optical Simulation of Bifacial Solar Cells
  2012 Energy Proceedia, volume: 27, pages: 300 - 305
• A. Nimo, D. Grgic, L.M. Reindl
  Optimization of Passive Low Power Wireless Electromagnetic Energy Harvesters
  2012 Sensors 2012, volume: 12, issue: 1, pages: 13636 - 13663.
  » show abstract« hide abstract
  Abstract

  This work presents the optimization of antenna captured low power radio frequency (RF) to direct current (DC) power converters using Schottky diodes for powering remote wireless sensors. Linearized models using scattering parameters show that an antenna and a matched diode rectifier can be described as a form of coupled resonator with different individual resonator properties. The analytical models show that the maximum voltage gain of the coupled resonators is mainly related to the antenna, diode and load (remote sensor) resistances at matched conditions or resonance. The analytical models were verified with experimental results. Different passive wireless RF power harvesters offering high selectivity, broadband response and high voltage sensitivity are presented. Measured results show that with an optimal resistance of antenna and diode, it is possible to achieve high RF to DC voltage sensitivity of 0.5 V and efficiency of 20% at −30 dBm antenna input power. Additionally, a wireless harvester (rectenna) is built and tested for receiving range performance.
• K. Rühle, M. Rauer, M. Rüdiger, J. Giesecke, T. Niewelt, C. Schmiga, S.W. Glunz, M. Kasemann
  Passivation Layers for Indoor Solar Cells at Low Irradiation Intensities
  2012 Energy Procedia, volume: 27, pages: 404 - 411
  » show abstract« hide abstract
  Abstract

  The passivation mechanisms and qualities of Al2O3, SiNx, SiO2 and a-Si:H(i) on p- and n-type silicon are investigated by quasi-steady-state photoluminescence measurements. This technique allows effective lifetime measurements in an extremely large injection range between 1010 cm-3 and 1017 cm-3. The measurements are discussed focusing on injections below 1012 cm-3 in order to determine the most effective passivation layer for solar cells arranged for indoor applications. Fixed negative charges in the passivation layer cause field-effect passivation due to band bending leading to either accumulation or inversion at the passivation layer/silicon interface. Accumulation causes a stable passivation quality at low level injection. Inversion leads to effective lifetime losses similar to the losses in the space charge region. On p-type silicon the most effective surface passivation at low injections is provided by Al2O3 or a-Si:H(i). The n-type silicon samples passivated with a-Si:H(i) show the best effective lifetimes. SiNx and SiO2 show lifetimes one order of magnitude below a-Si:H(i). Al2O3 on n-type is the most effective passivation at high injections around 1015 cm-3. Due to inversion losses at low level injections the passivation quality decreases more than two orders of magnitude for injections around 1010 cm-3.
• A. Yousaf, F.A Khan, L.M Reindl
  Passive Wireless Sensing of Micro coil parameters in fluidic environments
  2012 Sensors and Actuators 2012
• J. Hiller, M. Maisl, L. M. Reindl
  Physical characterization and performance evaluation of an x-ray micro-computed tomography system for dimensional metrology applications
  2012 Measurement Science and Technology, issue: 23, page: 18 pp
  » show abstract« hide abstract
  Abstract

  This paper presents physical and metrological characterization measurements conducted for an industrial x-ray micro-computed tomography (CT) system. As is well known in CT metrology, many factors, e.g., in the scanning and reconstruction process, the image processing, and the 3D data evaluation, influence the dimensional measurement properties of the system as a whole. Therefore, it is important to know what leads to, and what are the consequences of, e.g., a geometrical misalignment of the scanner system, image unsharpness (blurring), or noise or image artefacts. In our study, the two main components of a CT scanner, i.e. the x-ray tube and the flat-panel detector, are characterized. The contrast and noise transfer property of the scanner is obtained using image-processing methods based on linear systems theory. A long-term temperature measurement in the scanner cabinet has been carried out. The dimensional measurement property has been quantified by using a calibrated ball-bar and uncertainty budgeting. Information about the performance of a CT scanner system in terms of contrast and noise transmission and sources of geometrical errors will help plan CT scans more efficiently. In particular, it will minimize the user's influence by a systematic line of action, taking into account the physical and technical limitations and influences on dimensional measurements.
• Fischer S., Hallermann F., Eichelkraut T., von Plessen G., Krämer K.W., Biner D., Steinkemper H., Hermle M., Goldschmidt J.C.
  Plasmon enhanced upconversion luminescence near gold nanoparticles-simulation and analysis of the interactions
  2012 Opt Express, volume: 21, pages: 271 - 281
• Q. Hamp, O. Gorgis, P. Labenda, M. Neumann, T. Predki, L. Heckes, A. Kleiner, L.M. Reindl
  Study of efficiency of USAR operations with assistive technologies
  2012 Journal of Advanced Robotics

2011

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• F. Höflinger, M. Törk, A. Ojha, L.M. Reindl
  Drivability enhancement of transport buses using an auxiliary system with an IMU
  2011 International Journal of Electrical & Computer Sciences (IJECS), volume: 11, issue: 06, pages: 01 - 07
• J. Hiller, T.O.J. Fuchs, S. Kasperl, L.M. Reindl
  Einfluss der Bildqualität röntgentomographischer Abbildungen auf Koordinatenmessungen: Grundlagen, Messungen und Simulationen
  2011 tm - Technisches Messen,, issue: 7-8, pages: 334 - 347
• Goldschmidt J.C., Fischer S., Löper P., Krämer K.W., Biner D., Hermle M., Glunz S.W.
  Experimental analysis of upconversion with both coherent monochromatic irradiation and broad spectrum illumination
  2011 Sol Energ Mat Sol C, volume: 95, pages: 1960 - 1963
• R. Zhang, M. Loschonsky, L.M. Reindl
  Study of Zero Velocity Update for Both Low- and High-Speed Human Activities
  2011 International Journal of E-Health and Medical Communications, volume: 2, issue: 2, pages: 46 - 67
• A. Yousaf, T. Jäger, L.M. Reindl
  Wireless Measurement System for Extracting Open Loop Micro Coil Parameters
  2011 FREQUENZ, Journal of RF/Microwave Engineering, Photonics and Communications
• A. Yousaf, F.A. Khan, L.M. Reindl
  Wireless Sensing of Open Loop Micro Inductors Using Helmholtz Coil
  2011 International Journal on Smart Sensing and Intelligent Systems ISSN 1178568, issue: 4, supplement: 4

2010

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• R. Nopper, R. Has, L.M. Reindl
  A Wireless Sensor Readout System - Circuit Concept, Simulation and Accuracy
  2010 Ieee T Instrum Meas
• M.C. Schubert, W. Kwapil, J. Schön, H. Habenicht, M. Kasemann, P. Gundel, M. Blazek, W. Warta
  Analysis of performance limiting material properties of multicrystalline silicon
  2010 olar Energy Materials and Solar Cells, volume: 94, issue: 9, pages: 1451 - 1456
• O. Breitenstein, J. Bauer, J.M. Wagner, N. Zakharov, H. Blumtritt, A. Lotnyk, M. Kasemann, W. Kwapil, W. Warta
  Defect-Induced Breakdown in Multicrystalline Silicon Solar Cells
  2010 IEEE Transactions on Electron Devices, volume: 57, pages: 2227 - 2234
• Fischer S., Goldschmidt J.C., Löper P., Bauer G.H., Brüggemann R., Krämer K.W., Biner D., Hermle M., Glunz S.W.
  Enhancement of silicon solar cell efficiency by upconversion: Optical and electrical characterization
  2010 J Appl Phys, volume: 108, page: 044912
• U. Siebold, M. Larisch, I. Häring
  Nutzung von SysML zur Sicherheitsanalyse
  2010 apt edition - Automatisierungstechnische Praxis, volume: 52, issue: 12, pages: 54 - 61
• J.A. Giesecke, M. Kasemann, M.C. Schubert, P. Würfel, W. Warta
  Separation of local bulk and surface recombination in crystalline silicon from luminescence reabsorption
  2010 Progress in Photovoltaics: Research and Applications, volume: 18, issue: 1, pages: 10 - 19
• M. Glatthaar, J. Haunschild, M. Kasemann, J. Giesecke, W. Warta, S. Rein
  Spatially resolved determination of the dark saturation current and the series resistance of silicon Solar Cells
  2010 Physica Status Solidi Rapid Research Letters, volume: 4, pages: 13 - 15
• Heinrich, M, Dahms, T, Flunkert, V, Teitsworth, SW, Schöll, E
  Symmetry-breaking transitions in networks of nonlinear circuit elements
  2010 New Journal of Physics, volume: 12, issue: 11, page: 113030
• R. Nopper, R. Niekrawietz, L.M. Reindl
  Wireless Readout of Passive LC Sensors
  2010 IEEE Transactions on Instrumentation and Measurement, volume: 59, pages: 2450 - 2457

2009

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• S. Kasperl, J. Hiller
  Artefaktkorrekturen beim dimensionellen Messen mit industrieller Röntgen-Computertomographie
  2009 Tm-tech Mess, volume: 09/2009, page: 401
  » show abstract« hide abstract
  Abstract

  The non-destructive inspection of complex components is an important task in industrial production. The requirements comprise a fast verification of the dimensional accuracy as well as the analysis of nominal/actual value comparisons. To meet these requirements Computed Tomography (CT) is best suited as a non-destructive testing method. However with this method physical effects, like beam hardening and scattered radiation, are causing artefacts within the reconstructed slices that reduce image quality and that make it difficult, if not impossible, to perform the aforementioned inspection task. This contribution describes how, by using Iterative Artefact Reduction (IAR), the quality of reconstruction can be improved. Using a special reference body and an aluminium test body selected parameters and measurands are obtained and the achieved increase in precision is quantified.
• J.A. Giesecke, M. Kasemann, W. Warta
  Determination of local minority carrier diffusion lengths in crystalline silicon from luminescence images
  2009 J Appl Phys, volume: 106, issue: 1, page: 014907
• W. Kwapil, M. Kasemann, P. Gundel, M.C. Schubert, W. Warta, P. Bronsveld, G. Coletti
  Diode breakdown related to recombination active defects in block-castmulticrystalline silicon solar cells
  2009 J Appl Phys, volume: 106, page: 06353
• J. Haunschild, M. Glatthaar, M. Kasemann, S. Rein, E.R. Weber
  Fast series resistance imaging for silicon solar cells using electroluminescence
  2009 Physica Status Solidi Rapid Research Letters, volume: 3, pages: 227 - 229
• M. Freunek, M. Freunek(Müller), T. Ungan, W. Walker, L.M. Reindl
  New Physical Model for Thermoelectric Generators
  2009 J Electron Mater, volume: 38, issue: 7, page: 1214
  » show abstract« hide abstract
  Abstract

  In this paper we describe a new analytical physical model for thermoelectric generators (TEGs). The model includes the Thomson effect, the Peltier heat, a parameterization of the Joule heat, as well as all thermal and electrical resistances. Geometry optimization and investigations of the influence of Peltier heat and the heat source, as well as heat sink conditions and the load resistance, which affect the output power, are presented. The results are compared with measurements of commercially available thermoelectric generators and the fundamental thermodynamic limit. A comparison between the generators is performed.
• T.E. Zander, V. Madyastha, A. Patil, P. Rastogi, L.M. Reindl
  Phase step estimation in interferometry via an unscented Kalman filter
  2009 Opt Lett
  » show abstract« hide abstract
  Abstract

  This Letter presents an unscented Kalman filter to identify phase step imparted to a piezoelectirc transducer (PZT) in phase shifting interferometry in the presence of Gaussian noise. The advantage of the proposed algorithm lies in its ability to determine the phase step values between 0 and π radians without any prior calibration of the piezoelectric device. The algorithm is tested rigorously using the simulated data in the presence of Gaussian distributed noise. Experimental validations are also performed in a holographic interferometry optical set up to verify the proposed approach. Once the phase step is identified, the interference phase can be estimated using the least squares fitting approach. © 2009 Optical Society of America
• S. Kontermann, M. Hörteis, M. Kasemann, A. Grohe, R. Preu, E. Pink, T.Trupke
  Physical understanding of the behavior of silver thick film contacts on n-type siicon under annealing conditions
  2009 Solar Energy Materials & Solar Cells, volume: 93, pages: 1630 - 1635
• J. Albesa, M. Gasulla, J. Higuera, M.T. Penella, J. Polo
  REALnet: An environmental Wireless Sensor Network
  2009 Pervasive Computing Approaches to Environmental Sustainability, volume: 8, page: 55
• M. Kasemann, B. Walter, W. Warta
  Reliable hot-spot classification in 10 milliseconds using ultra-fast lock-in thermography
  2009 Progress in Photovoltaics: Research and Applications, volume: 17, pages: 441 - 450
• J.A. Giesecke, M. Kasemann, W. Warta
  Separation of Local Bulk and Surface Recombination in Crystalline Silicon from Luminescence Reabsorption
  2009 Prog Photovoltaics, pages: 10 - 19
• J.A. Giesecke, M. The, M. Kasemann, W. Warta
  Spatially resolved characterization of silicon as-cut wafers with photoluminescence imaging
  2009 Progress in Photovoltaics: Research and Applications, volume: 17, issue: 4, pages: 217 - 225
• M. Glatthaar, J.A. Giesecke, M. Kasemann, J. Haunschild, M. The, S. Rein, W. Warta
  Spatially resolved determination of the dark saturation current of silicon solar cells from electroluminescence images
  2009 J Appl Phys, volume: 105, issue: 11, pages: 113110 - 113115
• M. Freunek(Müller), M. Freunek, T. Ungan, L.M. Reindl
  Wandler für energieautarke Mikrosysteme
  2009 Tm-tech Mess, issue: 12, pages: 532 - 539

2008

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• M. Kasemann, B. Walter, C. Meinhardt, J. Ebser, W. Kwapil, W. Warta
  Emissivity-corrected power loss calibration for lock-in thermography measurements on silicon solar cells
  2008 J Appl Phys, volume: 103, supplement: 113503
• T. Jäger, M. Hobler, D. Ruf, F. Timmler
  Funksensoren mit induktiver Energieversorgung im Maschinenbau
  2008 Fachzeitschrift HF-Report, pages: 44 - 49
• M. Kasemann, D. Grote, B. Walter, W. Kwapil, T. Trupke, Y. Augarten, R.A. Bardos, E. Pink, M.D. Abbott, W. Warta
  Luminescence imaging for the detection of shunts on silicon solar cells
  2008 Progress in Photovoltaics: Research and Applications, volume: 16, issue: 4, pages: 297 - 305
• W.D. Walker
  Near-field Electromagnetic Effects on Einstein Special Relativity
  2008 Galilean Electrodynamics physics journal

2007

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• L. Paganini, P. Hartogh, L.M. Reindl
  An improved method for nonlinearity detection applied to a new 400-MHz bandwidth Chirp Transform Spectrometer
  2007 Transactions on Systems, Signals and Devices
  » show abstract« hide abstract
  Abstract

  A novel method for detecting possible nonlinearities which could affect the overall behavior of microwave systems, for instance in the power density accuracy, is analyzed and applied to a recently developed 400-MHz bandwidth chirp transform spectrometer (CTS) with 100 kHz spectral resolution. After a description of the instrument’s design and characterization, we provide test spectra obtained during observation campaigns performed in atmospheric science, i.e. by using a 142-GHz ozone system. These results allow an intercomparison of the responses given by different CTS-backend systems, and hence the chance to address the issue of possible nonlinearities. A description of this new approach is discussed by showing the capability to identify and suppress unwanted nonlinear behaviors, and consequently its improvements in the spectrometer’s performance.
• J. Hiller, S. Reisinger, F. Sukowski, T. Meier, L.M. Reindl
  Analytical simulation of internal X-ray scatter radiation in flat-panel detectors using adaptive filter kernels
  2007 Journal of Latex Class Files, volume: 6, issue: 1
• T. Jäger, R. Huber
  Einsatz der Mikrosystemtechnik zur Zustands- und Prozessüberwachung im Anlagen und Maschinenbau
  2007 Fachzeitschrift für Rohstoff, Bergbau und Energie Glückauf
• J. Bardong, R. Fachberger, G. Bruckner, L.M. Reindl
  High temperature RFID System using passive SAW transponders
  2007 Proceedings of the European Microwave Association, Special Issue on RFID Systems
• J. Hiller, S. Kasperl, U. Hilpert, M. Bartscher
  Koordinatenmesung mit industrieller Computertomografie
  2007 Tm-tech Mess, volume: 74, issue: 11, pages: 553 - 564
• J. Hiller, S. Kasperl
  Modellierung und Messung von Kenn- und Einflussgrößen in der Computertomographie
  2007 PTB Bericht F-54, pages: 137 - 152
• L.M. Reindl
  Unwired SAW Sensors Systems
  2007 Proc. European Microwave Association (EuMA), volume: 3, pages: 110 - 119
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices can be used as identification and sensor elements (SAW transponders) for measuring physical, chemical and biological quantities such as temperature, pressure, torque, acceleration, humidity, etc. that do not need additional power supply for the sensor elements and may be accessed wirelessly. The complete wireless sensor system includes a transponder, consisting of an antenna wired to a SAW device, and a local reader unit, consisting of a radar transceiver linked to a signal processing and controlling unit. An RF burst transmitted by the radar transceiver is received by the passive SAW transponder. The passive transponder responses with an RF signal - like a radar echo, which can be received by the front-end of the local transceiver. Amplitude, frequency, phase, and time of arrival of this RF response signal carry information about the SAW reflection and propagation mechanisms which in many cases can be directly attributed to the sensor effect for a certain measurand. Due to the high delay time of the SAW transponder in the order of a few µs, usually no intersymbol interferences (ISI) due to environmental reflections occur when the system operates in typical, i.e. harsh indoor/outdoor environments. The present work reviews the operating principle of such sensor systems and their state-of-the-art performance by way of a few examples which include the wireless measurement of temperature, pressure, torque, acceleration, tire-road friction, magnetic field, and water content of soil.

2006

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• G. L. Villanueva, P. Hartogh, L.M. Reindl
  A digital dispersive matching network for SAW devices in Chirp Transform Spectrometers
  2006 Ieee T Microw Theory, volume: 54, issue: 4, pages: 1415 - 1424
  » show abstract« hide abstract
  Abstract

  The performance of a chirp transform spectrometer can be significantly improved through a digital dispersive matching network. In this paper, we present the development of a new design, the adaptive digital chirp processor (ADCP), which generates an expander chirp signal with dispersive characteristics matching those of the surface acoustic wave filter behaving as a compressor/ convolver. This matching signal (i.e., the chirp) is generated by a digital direct synthesizer and is then bandpass filtered, level regulated, up-converted, and frequency tripled in order to achieve the required bandwidth of 430 MHz. The design of the matching network and the signal processing of the resulting dispersive signal demanded a rational and optimum combination of different technologies, such as quadrature modulation, high-performance spectral filtering, ultra-stable frequency sources, and a theoretical analysis of the circuit design by using a numerical model of the ADCP.
• M. Kasemann, M.C. Schubert, M. The, M. Köber, M. Hermle, W. Warta
  Comparison of luminescence imaging and illuminated lock-in thermography on silicon solar cells
  2006 Appl Phys Lett, volume: 89, supplement: 224102
• U. Weik
  FPGAs in Theorie und Praxis: Teil 1: Hochkomplexe anwenderprogrammierbare Logikschaltungen (FPGAs) – Aufbau und Strukturen
  2006 Elektronik, volume: 06/2006, pages: 46 - 48
• U. Weik
  FPGAs in Theorie und Praxis: Teil 2: Soft-Prozessorkerne für FPGAs – Wie sie funktionieren und was sie leisten
  2006 Elektronik, volume: 21/2006, pages: 48 - 50
• H. Qasem, L.M. Reindl
  Nonlinear indoor tracking with range only measurements based on high frequency radar
  2006 WSEAS Journal on Signal Processing, pages: 1343 - 1350
• S. Schuster, S. Scheiblhofer, L.M. Reindl, A. Stelzer
  Performance Evaluation of Algorithms for SAW Based Temperature Measurement
  2006 Ieee T Ultrason Ferr, volume: 53, issue: 6, pages: 1177 - 1185
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  Abstract

  Whenever harsh environmental conditions such as high temperatures, accelerations, radiation, etc., prohibit usage of standard temperature sensors, surface acoustic wave-based temperature sensors are the first choice for highly reliable wireless temperature measurement. Interrogation of these sensors is often based on frequency modulated or frequency stepped continuous wave-based radars (FMCW/FSCW). We investigate known algorithms regarding their achievable temperature accuracy and their applicability in practice. Furthermore, some general rules of thumb for FMCW/FSCW radar-based range estimation by means of the Cramer-Rao lower bound (CRLB) for frequency and phase estimation are provided. The theoretical results are verified on both simulated and measured data.

2005

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• Th. Hesjedal, J. Mohanty, F. Kubat, W. Ruile, L.M. Reindl
  A Microscopic View on Acoustomigration
  2005 Ieee T Ultrason Ferr, volume: 52, issue: 9, pages: 1584 - 1593
  » show abstract« hide abstract
  Abstract

  Stress-induced material transport in surface acoustic wave devices, so-called acoustomigration, is a prominent failure mechanism, especially in high-power applications. We used scanning probe microscopy techniques to study acoustomigration of metal structures in-situ, i.e., during the high-power loading of the device. Scanning acoustic force microscopy (SAFM) allows for the simultaneous measurement of the acoustic wavefield and the topography with submicron lateral resolution. High-resolution microscopy is essential as acoustomigration is a phenomenon that not only results in the formation of more macroscopic voids and hillocks but also affects the microscopic grain structure of the film. We present acoustic wavefield and topographic image sequences giving a clear insight into the nature of the film damage on a submicron scale. The 900 MHz test structures were fabricated on 36° YX-lithium tantalate (YX-LiTaO3) and incorporated 420-nm thick aluminium (Al) electrodes. By correlating the acoustic wavefield mapping and the local changes in topography, we confirmed model calculations that predict the correspondence of damage and stress (i.e., hillocks and voids) are preferentially formed in areas of high stress. The way the film is damaged does not significantly depend on the applied power (for typical power levels used in this study). Furthermore, acoustomigration leads to smoother surfaces via lateral grain growth. Another contribution to the grain dynamics comes from the apparent grain rotation in the highly anisotropic stress field of an acoustic wave. Thus, through in-situ scanning probe microscopy techniques, one can observe the initial changes of the grain structure in order to obtain a more detailed picture of the phenomenon of acoustomigration.
• F. Kubat, W. Ruile, U. Rösler, L.M. Reindl
  A numerical method for calculating the dynamic stress in SAW devices Microelectronic Engineering
  2005 SAW devices Microelectronic Engineering, volume: 82, issue: 3-4, pages: 670 - 674
• E. Mackensen, W. Kuntz
  Bluetooth, ZigBee und nanoNET: Die aktuellen WPAN Techniken im Vergleich
  2005 Elektronik, volume: 24, pages: 70 - 72
• E. Mackensen, W. Kuntz
  Funktechniken für drahtlose Sensor-Aktor-Netzwerke
  2005 Elektronik Wireless, pages: 29 - 31
• F. Kubat, W. Ruile, C. Eberl, T. Hesjedal, L.M. Reindl
  Qualitative and quantitative analysis of acoustomigration effects in SAW-devices Microelectronic Engineering
  2005 SAW-devices Microelectronic Engineering, volume: 82, issue: 3-4, pages: 655 - 659

2004

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• R. Fachberger, G. Bruckner, G. Knoll, R. Hauser, J. Biniasch, L.M. Reindl
  Applicability of LiNbO3, Langasite and GaPO4 in High Temperature SAW Sensors Operating at Radio Frequencies
  2004 Ieee T Ultrason Ferr, volume: 51, issue: 11, pages: 1427 - 1431
  » show abstract« hide abstract
  Abstract

  The applicability of LiNbO3, langasite and GaPO4 for use as crystal substrates in high temperature surface acoustic wave (SAW) sensors operating at radio frequencies was investigated. Material properties were determined by the use of SAW test devices processed with conventional lithography. On GaPO4, predominantly surface defects limit the accessible frequencies to values of 1 GHz. Langasite SAW devices could be operated up to 3 GHz; however, high acoustic losses of 20 dB/µs were observed. On LiNbO3, the acoustic losses measured up to 3.5 GHz are one order of magnitude less. Hence, SAW sensors capable of wireless interrogation were designed and processed on YZ-cut LiNbO3. The devices could be successfully operated in the industrial-scientific-medical (ISM) band from 2.40 to 2.4835 GHz up to 400°C.
• F. Kubat, W. Ruile, T. Hesjedal, J. Stotz, U. Rösler, L.M. Reindl
  Calculation and Experimental Verification of the Acoustic Stress at GHZ Frequencies in SAW Resonators
  2004 Ieee T Ultrason Ferr, volume: 51, issue: 11, pages: 1437 - 1448
  » show abstract« hide abstract
  Abstract

  High power applications of Surface Acoustic Wave (SAW) devices may lead to acoustomigration in their thin metal electrodes, which deteriorates the performance or may even destroy the SAW device. It is confirmed in this paper that the mechanism of acoustomigration is caused by the SAW-induced stress in the metal. The quantitative calculation of this stress will be shown in detail, starting from the widely used P-Matrix model as a standard analysis tool. The combination with the partial wave method (PWM) yields the stress distribution inside the metal. This approach provides the flexibility to determine the stresses for any given point in a SAW device, for any input power, frequency, wavetype, device geometry, or metal layer. In order to confirm the absolute values of the stress components, we calculated and measured displacements as a function of input power and frequency.
• P.K. Khanna, B. Hornbostel, T. Jäger, W. Schäfer
  Low Temperature Cofired Ceramics (LTCC): An Emerging Technology for MEMS and Micro-system Production
  2004 MST News, Int. Magazine on Smart Systems Technology, issue: 4, pages: 40 - 41
• L.M. Reindl, I.M. Shrena
  Wireless Measurement of Temperature Using Surface Acoustic Waves Sensors
  2004 Ieee T Ultrason Ferr, volume: 51, issue: 11, pages: 1457 - 1463
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices can be used as wireless sensor elements, called SAW transponders, for measuring physical quantities such as temperature that do not need any power supply and may be accessed wirelessly. A complete wireless sensor system consists of one or more such SAW transponders and a local radar transceiver. The SAW transponder receives an RF burst in the VHF/UHF band transmitted by the radar transceiver. The reader unit performs a radar measurement of the impulse response of the SAW transponder via a high-frequency electromagnetic radio link. A temperature variation changes the SAW velocity and thereby the response pattern of the SAW device. By analyzing the time delay between backscattered pulses with different time delays we get a rough estimation of the temperature of the SAW transponder. By using this information the ambiguity of ±2π in the phase differences between the pulses can be eliminated, which provides an overall and unambiguous temperature resolution of ±0.2°C.

2003

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• M. Huemer, R. Weigel, L.M. Reindl
  A Review of Cyclically Extended Single Carrier Transmission with Frequency Domain Equalization for Broadband Wireless Transmission
  2003 Eur T Telecommun, volume: 14, pages: 329 - 341
  » show abstract« hide abstract
  Abstract

  In this paper we investigate the concept of cyclically extended single carrier transmission with frequency domain equalization (SC/FDE). We present a detailed mathematical derivation of fast Fourier transform (FFT) based optimum linear receivers, and we describe the signal processing steps of an efficient FDE implementation structure. With a specific system design, where the parameters have been adapted to the IEEE 802.11a and Hiperlan/2 orthogonal frequency division multiplexing (OFDM) based wireless local area network (WLAN) standards in the 5 GHz band, we demonstrate that SC/FDE is a powerful candidate for high speed wireless future applications. Copyright © 2003 AEI.
• E. Mackensen, W. Kuntz
  Einfacher Zugang zur Analogwelt; Teil 1: Ein Einblick in die programmierbare Analogtechnik mit Vergleich der Chips auf dem Markt
  2003 Elektronik 2003, issue: 14, pages: 68 - 70
• E. Mackensen, W. Kuntz
  Einfacher Zugang zur Analogwelt; Teil 2: Programmierbare Analogtechnik - Parameter und Anwendungsmöglichkeiten
  2003 Elektronik 2003, issue: 15, pages: 50 - 52
• E. Mackensen, D. Arnold, W. Kuntz
  FPAAs und PSoCs für die analoge Signalaufbereitung von Sensor-/Aktordaten in intelligenten, autarken Mikrosystemen
  2003 Analog
  » show abstract« hide abstract
  Abstract

  Kern des Beitrags ist die Vorstellung der Möglichkeiten, wie die analoge Signalaufbereitung von Sensor-/ Aktordaten in intelligenten, autarken Mikrosystemen mittels Field-Programmable-Analog-Arrays (FPAAs) und Programmable-Systems-on-Chip (PSoCs) vereinfacht werden kann. Unter intelligenten, autarken Mikrosystemen versteht man Mikrosysteme, welche die Daten mehrerer Sensoren aufnehmen und verarbeiten können, mehrere Aktoren ansteuern können, eine gewisse Intelligenz besitzen, energieautark sind und mit einer großen Anzahl anderer Systeme drahtlos kommunizieren können. Analogschaltungen bilden in derartigen Mikrosystemen das Interface der realen analogen Welt (Sensoren/Aktoren) zur digitalen Elektronik, z.B. einem Mikrorechner. Die Schwerpunkte bei der Vorstellung der in Frage kommenden FPAAs und PSoCs liegen dabei auf der Betrachtung wichtiger analoger Parameter, wie z.B. Linearität, Rauschen, Leistungsaufnahme, Bandbreite, Stabilität, Temperaturdrift, Offset und Reproduzierbarkeit, da diese die Güte und den Einsatzbereich eines durch FPAAs / PSoCs realisierten Systems letztendlich bestimmen. An Hand der konkreten Entwicklung eines Sensor-/Aktor-Interfaces werden zudem die Anwendungsmöglichkeiten aufgezeigt.
• G. Scholl, C. Korden, E. Riha, C.C.W. Ruppel, U. Wolff, G. Riha, L.M. Reindl, R. Weigel
  SAW Based Radio Sensor Systems for Short-Range Applications
  2003 IEEE Microwave Magazine, volume: Dec 2003, pages: 60 - 76

2002

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• C.C.W. Ruppel, L.M. Reindl, R. Weigel
  SAW Devices and Their Wireless Communications Applications
  2002 IEEE microwave Magazine, volume: June2002, pages: 65 - 71

2001

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• L.M. Reindl, R. Steindl, C. Hausleitner, A. Pohl, G. Scholl
  Passive funkauslesbare Sensoren
  2001 Tm-tech Mess, volume: 68, issue: 5, pages: 240 - 246
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave elements can be used in identification and sensor devices (SAW transponders). They do not require a power supply and can be wirelessly interrogated. The present work reviews the operating principle of these sensor systems and their state-of-the-art performance by some examples which include wireless measurement of temperature, pressure, acceleration, magnetic field, and water content of soil.
• L.M. Reindl, A. Pohl, G. Scholl, R. Weigel
  SAW Based Radio Sensor Systems
  2001 IEEE Sensors Journal, volume: 1, issue: 1, pages: 69 - 78
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices can be used as identification and sensor elements (SAW transponders) for measuring physical quantities such as temperature, pressure, torque, acceleration, humidity, etc., that do not need any power supply and may be accessed wirelessly. The complete wireless sensor system consists of such a SAW transponder and a local radar transceiver. An RF burst transmitted by the radar transceiver is received by the antenna of the SAW transponder. The passive transponder responds with an RF signal—like a radar echo—which can be received by the front-end of the local transceiver. Amplitude, frequency, phase and time of arrival of this RF response signal carry information about the SAW reflection and propagation mechanisms which in many cases can be directly attributed to the sensor effect for a certain measurand. Usually no intersymbol interference (ISI) due to environmental echoes occur, due to the high delay time of the SAW transponder in the order of some µs. The present work reviews the operating principles of such sensor systems and their state-of-the-art performance by way of some examples which include the wireless measurement of temperature, pressure, torque, acceleration, tire-road friction, magnetic field, and water content of soil.
• L.M. Reindl
  Sensoren drahtlos abgefragt
  2001 Technologie-Informationen niedersächsischer Hochschulen
• W.-E. Bulst, G. Fischerauer, L.M. Reindl
  State of the art in wireless sensing with surface acoustic waves
  2001 Ieee T Ind Electron, volume: 48, issue: 2, pages: 265 - 271
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices can be turned into novel identification and sensor elements (transponders) that do not need any power supply and may be interrogated wirelessly. Such a transponder picks up an electromagnetic request signal and stores it until all echoes caused by multi-path propagation have died away. Then, a characteristic response signal is beamed back to the interrogator unit. In radio-link sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. – This contribution surveys the operating principle of such sensors and their state-of-the-art performance. The discussion is supported by illustrative examples such as temperature sensors and sensors for mechatronic applications.
• L.M. Reindl
  Über Funk auslesbare passive Sensoren
  2001 ITZ Berichte, volume: 1, issue: 3, pages: 1 - 16
  » show abstract« hide abstract
  Abstract

  Mittels Oberflächenwellen (OFW)-Bauelemente werden miniaturisierte mikroakustische Identifikations- und Sensorelemente (Transponder) ermöglicht, die ohne eigene Stromversorgung telemetrisch abgefragt werden können (OFW-Funksensorik). In dem Beitrag wird das Funktionsprinzip dieser Transponder erläutert. Als Anwendungsbeispiele werden Identmarken sowie Sensoren für Temperatur, Druck, Beschleunigung, Magnetfelder und ein Sensor zur Ermittlung der Bodenfeuchte gezeigt.

2000

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• L.M. Reindl, C.C.W. Ruppel, S. Berek, U. Knauer, M. Vossiek, P. Heide, L. Oréans
  Design, fabrication, and application of precise SAW delay lines used in a FMCW radar system
  2000 Ieee T Microw Theory, volume: 49, issue: 4, pages: 787 - 794
  » show abstract« hide abstract
  Abstract

  An inexpensive frequency-modulated continuous- wave (FMCW) radar system is presented in this paper, which, nevertheless, meets all industrial requirements. The FMCW radar uses a low-cost nonlinear voltage-controlled oscillator (VCO), operating at an IF of 2.45 GHz to generate the frequency modulation of the radar system. This VCO signal is applied twice, first to generate the radar transmitter signal at 24 GHz, and then it is fed to a surface acoustic wave (SAW) delay line. The SAW delay line generates a fixed delay time, which corresponds with a fixed radar distance. Thus, all systematic nonlinearities and stochastic phase errors of the FMCW system can be monitored and, afterwards, can be compensated for in real time. This linearization technique leads to a significant enhancement in dynamic range for a FMCW radar system. For this FMCW system, SAW delay lines with a linear phase characteristic have been designed using a linear optimization program. The delay line consists of two chirped and weighted interdigital transducers. For high volume, low-cost, and high-yield production of the required SAW structures, with linewidths down to 0.3 µm, technological improvements had to be achieved, especially in photolithography. Based on these design and fabrication techniques, delay lines at 2.45 GHz operating at the fundamental and third harmonic with bandwidths up to 800 MHz have been realized.
• L.M. Reindl, C.C.W. Ruppel, A. Kirmayr, N. Stockhausen, M.A. Hilhorst, J. Balendonck
  Radio Requestable Passive SAW Water Content Sensor
  2000 Ieee T Microw Theory, volume: 49, issue: 4, pages: 803 - 808
  » show abstract« hide abstract
  Abstract

  A new passive sensor for remote measurement of water content in sandy soil was designed, using a surface acoustic wave (SAW) reflective delay line. Information from this sensor can be obtained by an interrogation device via a radio link operating in the European 434-MHz industrial–scientific–medical band. The SAW device, manufactured on the YZ cut of LiNbO3, is mounted and sealed in a standard dual inline 16 package and contains four electroacoustic transducers. One transducer is connected to an external antenna to pick up an RF request signal from the interrogation device and to send back an RF response. The second transducer operates as a reflector. The bus bars of this transducer are connected with two measuring rods through an electrical transmission line. These rods can be inserted into sandy soil. The final two transducers operate as reflectors and are included for reference purposes. The transmission line and the two rods spanning the sand–water mixture have a characteristic impedance Zload, which loads the second transducer. Changes in the soil water content are observed as a change of the total permittivity due to the high permittivity of free water, which, in turn, affects Zload as well. The amplitude and phase of the acoustic reflection at the second transducer changes due to a variation of the terminating Zload. This then results in a difference in attenuation and phase of the corresponding peak in the time domain. Thus, the RF response of the sensor carries information about the water content between the rods, which, therefore, can be detected by and evaluated in the interrogation unit.

1999

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• E.A. Mayer (Garova), A.A. Maradudin, A.P. Mayer
  Interaction of Rayleigh waves with randomly distributed oscillators on the surface
  1999 Phys Rev B, volume: 59, pages: 13291 - 13296
• A. Pohl, R. Steindl, L.M. Reindl
  The 'intelligent tire' utilizing passive SAW sensors - measurement of tire friction
  1999 Ieee T Instrum Meas, volume: 48, issue: 6, pages: 1041 - 1046
  » show abstract« hide abstract
  Abstract

  The term “intelligent tire” describes tires equipped with sensor systems to monitor thermal and mechanical parameters while driving. Information about temperature, tire pressure, tread wear, etc. is collected and used for car operation and maintenance support. The contact between tire and road surface is a key parameter when characterizing the ability to accelerate, decelerate and steer a vehicle, therefore making contact monitoring important for modern car control systems. Following numerous previous theoretical works, the friction coefficient can be measured by evaluating the mechanical strain in the tire surface contacting the road—utilizing the deformation of the tread elements. A new monitoring method using passive radio requestable SAW sensors is presented. The principle, measurement setup and experimental results are shown.
• L.M. Reindl, R. Weigel
  Wireless identification and sensing with surface acoustic waves
  1999 Recent Res. Devel. Microwave Theory & Tech., volume: 1, pages: 1 - 16
  » show abstract« hide abstract
  Abstract

  This paper surveys the operating principles of surface acoustic wave (SAW)-based wireless identification and sensing and the state-of-the-art performance by way of a few examples which include the remote measurement of temperature, pressure, torque, electrical current, and humidity.

1998

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• A. Springer, A. Pohl, W. Gugler, M. Huemer, L.M. Reindl, C. C. W. Ruppel, F. Seifert, R. Weigel
  A robust ultra broadband wireless communication system using SAW chirped delay lines
  1998 Ieee T Microw Theory, volume: 46, issue: 12, pages: 2213 - 2219
  » show abstract« hide abstract
  Abstract

  Design and performance of a low-cost wireless communication system for indoor and industrial environments are presented. The system is based on chirp-signal transmission to achieve a robust communication link. For the chirp expansion and compression, surface acoustic wave chirped delay lines fabricated from LiTaO3-X112rotY are used. Center frequency, bandwidth, and chirp rate are 348.8 MHz, 80 MHz, and ±40 MHz/µs, respectively. An optimized square-root weighting was chosen to reduce the sidelobes of the compressed pulse to -42 dB compared to the correlation peak. The chirp filters have been deployed in a hardware demonstrator for data rates of up to 5 Mb/s. Limiting factors for the data rate according to simulations and measurements are mainly intersymbol interferences due to the time overlapping of consecutive symbols and, to a lower extent, the multipath propagation.
• L.M Reindl, G. Scholl, T. Ostertag, H. Scherr, U. Wolff, F. Schmidt
  Theory and application of passive SAW radio transponder as sensors
  1998 Ieee T Ultrason Ferr, volume: 45, issue: 5, pages: 1281 - 1292
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation (i.e., no power-supply), and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond to an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. SAW radio transponders are advantageously placed on moving or rotating parts and in hazardous environments such as contaminated or high voltage areas. They also can be used for contactless measurements in high vacuum process chambers, under concrete, extreme heat, or strong radioactive radiation, where the use of conventional sensors is complicated, dangerous, or expensive. In this paper we discuss the principles of wireless passive SAW transponders and present a radio frequency interrogation unit and several passive radio SAWsensors developed for noncontact measurements of temperatures, pressures, torques, and currents.

1997

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• R. Weigel, F. Kalabic, G. Ostermayer, A. Pohl, F. Seifert, L.M. Reindl
  Design of SAW expander and compressor on LiTaO3 for a TCDMA spread spectrum system
  1997 Ieee T Microw Theory, volume: 45, issue: 12, pages: 2486 - 2492
  » show abstract« hide abstract
  Abstract

  We report on the design and performance of surfaceacoustic wave (SAW) minimum shift keying (MSK) tapped delay lines using pseudonoise code sequences with a length of 128 chips. As a substrate, X112°rotY-LiTaO3 has been used due to the system requirements of a given CDMA/TDMA (TCDMA) radio communication system. System IF frequency, bandwidth of the major lobe, and integration time of the SAW devices were, respectively, 360 MHz, 63.5 MHz, and 3 µs. We used SAW tapped delay lines employing nonweighted as well as cosine-weighted input interdigital transducers incorporating split-fingers. We designed both expander as well as compressor filters attaining very similar experimental results. We found insertion loss values down to 16 dB and amplitude ripples of less than 2 dB. The close-in selectivity was 28 dB.

1993

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• G. Müller, J. Machui, L.M. Reindl, R. Weigel, P. Russer
  Design for a low loss SAW reflector filter with extremely wide bandwidth for mobile communication systems
  1993 Ieee T Microw Theory, volume: 41, issue: 12, pages: 2147 - 2155
  » show abstract« hide abstract
  Abstract

  Design and performance of a new low loss surface acoustic wave (SAW) reflector filter are presented. The structure is a dual-track configuration incorporating two interdigital transducers (IDT’s) and reflectors in each track. Extremely wide bandwidth can be obtained if chirped IDT’s and reflectors are used. From the theoretical conditions for low loss operation of the reflector filter a design rule for the distances between the chirped components and for their lengths has been derived. Due to the fact that the transfer function of the filter is predominantly determined by the reflectors, we have developed a new synthesis method for chirped reflectors. For the design of the reflectors we used phase-weighting and finger width-weighting techniques in order to reduce passband distortions and to improve both the shape factor and the stopband rejection, The filter has been fabricated on 128° YX-LiNbO3. The center frequency and fractional bandwidth were 200 MHz and 10%, respectively. A minimum insertion loss of 4 dB, a small passband ripple of about 1 dB, and a stopband rejection better than 35 dB have been measured. Excellent agreement between simulation and measurement has been found.
• C.C.W. Ruppel, R. Dill, A. Fischerauer, G. Fischerauer, W. Gawlik, J. Machui, F. Müller, L.M. Reindl, W. Ruile, G. Scholl, I. Schropp, K.C. Wagner
  SAW devices for consumer communication applications
  1993 IEEE Trans. Ultrason. Ferroel. Freq. Control, volume: 40, issue: 5, pages: 438 - 452
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) filters are small, rugged, and crystal stable. They can be fabricated with high reproducibility. Today, more than a hundred million SAW TV IF filters are fabricated each year. SAW filters play a key role in the rapidly growing market of mobile communication systems and are used for channel filtering as well as for RF filtering. For these modern communication systems, novel types of SAW filters are being developed in order to meet the stringent requirements with respect to very low insertion loss, high relative bandwidths, and good stopband rejection properties. The trend toward higher frequencies for remote control systems makes SAW resonators advantageous for the frequency determining devices in these systems. A new application for SAW filters might be analog correlators in mobile telephones using code division multiple access (CDMA). As can be expected, this variety of different applications requires the full custom design of SAW devices. For this, efficient CAD tools are a prequisite.

1992

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• E. Mayer (Garova), V.P. Plesskii, A.V. Simonyan
  Scattering of surface acoustic waves by local surface resonances
  1992 Sov. J. Commun. Technol. Electron. (USA), volume: 37, pages: 79 - 93

1991

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• E. Mayer (Garova), V.P. Plesskii
  Reflection and scattering of Gulyaev-Bleustein waves at a resonant element
  1991 Sov. Phys.-Acoust. (USA), volume: 37, pages: 467 - 471
• E. Mayer (Garova), V.P. Plesskii, A.V. Simonyan
  Scattering of surface acoustic waves by local surface resonances
  1991 Translation of Radiotekh. Elektron. (Russia), volume: 36, pages: 1475 - 1488

1990

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• E. Mayer (Garova), V.P. Plesskii
  Reflection and scattering of Gulyaev-Bleustein waves at a resonant element
  1990 Sov. Phys.-Acoust. (USA), volume: 37, pages: 467 - 471
• E. Mayer (Garova), V.P. Plesskii
  Reflection and scattering of Gulyaev-Bleustein waves at a resonant element
  1990 Translation of Akust. Zh. (USSR), volume: 37, pages: 898 - 907
• E. Mayer (Garova), V.P. Plesskii
  Theory of Bragg reflection of Rayleigh surface acoustic waves from arrays with a smoothly varying period
  1990 Sov. Phys.-Acoust. (USA), volume: 36, pages: 473 - 476
• E. Mayer (Garova), V.P. Plesskii
  Theory of Bragg reflection of Rayleigh surface acoustic waves from arrays with a smoothly varying period
  1990 Translation of Akust. Zh. (USSR), volume: 36, pages: 847 - 852
• S.M. Balashov, E. Mayer (Garova), V.P. Plessky
  Theory of Rayleigh-waves Bragg reflection in quasiperiodic structures
  1990 Phys. Rev. B, volume: 59, pages: 11008 - 11016

1987

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• D.Ya. Stern, E. Mayer (Garova)
  Application of the correlation of incident and reflected cosmic radiation to the investigation of plasmaspheres of planets and the energy distribution of the radiation (in Russian)
  1987 Kosmicheskije issledovanija (USSR), volume: 25, pages: 332 - 334

1986

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• H.P. Graßl, L.M. Reindl, H.-W. Wörz
  CAD of precise SAW convolvers with high relative bandwith
  1986 Electron Lett, volume: 22, issue: 24, pages: 1288 - 1290
• E.A. Garova, A.I. Koslov, V.P. Plesskii
  Theory of the photothermal generation of Rayleigh waves
  1986 Translation of Akust. Zh. (USSR), volume: 32, pages: 310 - 316
• E. Mayer (Garova), A.I. Koslov, V.P. Plesskii
  Theory of the photothermal generation of Rayleigh waves
  1986 Sov.Phys.-Acoust. (USA), volume: 32, pages: 188 - 192

Reviews

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2013

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• Martin Kasemann
  Kamerabasierte quantitative Messverfahren für die Silizium-Photovoltaik — Was Licht über Solarzellen erzählt
  2013 Tm-tech Mess, volume: 80, issue: 4, pages: 111 - 122
• Michl, Bernhard, Kasemann, Martin, Warta, Wilhelm, Schubert, Martin C
  Wafer thickness optimization for silicon solar cells of heterogeneous material quality
  2013 Phys Status Solidi-r, volume: Early View

Books

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2014

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• AV Akademikerverlag
  Lokalisierungssystem basierend auf Galvanometer-Laserscannern
  ISBN: ISBN 978-3-639-45693-6
  J. Kokert
  » show abstract« hide abstract
  Abstract

  In hochkompetitiven Gewerben wird der stetige Warenfluss heutzutage durch fahrerlose Transportfahrzeuge (FTF) unterstützt. Die Lokalisierung dieser Fahrzeuge ist eine wesentliche Voraussetzung für deren Einsatz. Das System, welches in dieser Arbeit entwickelt wurde, soll mehrere FTF in Produktionshallen mit dynamischer Umgebung lokalisieren. Es besteht aus einem Laser-Scanner, welcher an der Decke montiert wird und mehreren Empfängern (MobileTags), die an den Transport-fahrzeugen befestigt werden. Basierend auf einem Lastenheft wurde ein neuartiges optisches Lokalisierungskonzept entwickelt und anhand von Überschlagsrechnungen die leistungsbezogenen Kenndaten ermittelt. Die Lokalisierung basiert auf dem Zusammenspiel von Laserscannen und Lasertracken. Durch das Scannen werden die mobilen Objekte im Messvolumen registriert. Das Tracken dient zum weiteren Verfolgen der Objekte und zur genauen Positionsbestimmung relativ zum Scanner. Dadurch wird sowohl eine hohe Aktualisierungsrate als auch eine hohe Genauigkeit erreicht. In diesem Buch wird die entwickelte Hardware und Software wie die Laseroptik, die Infrarot-Kommunikation zu den MobileTags, ein MobileTag-Demonstrator sowie die zentrale Steuerung des Scanners mit einem FPGA-Board und PowerPC vorgestellt. Die Evaluierung des Konzepts durch Messungen an der entwickelten Hardware rundet diese Arbeit ab.

2013

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• Springer-Verlag Berlin Heidelberg, page: 1559
  Sensortechnik, Handbuch für Praxis und Wissenschaft
  ISBN: ISBN 978-3-642-29941-4
  H.-R. Tränkler, L. M. Reindl
  » show abstract« hide abstract
  Abstract

  Das Handbuch ermöglicht Anwendern der Sensortechnik schnellen Zugriff auf fundiertes und aktuelles Fachwissen. Grundlagen und Anwendungen für alle Bereiche der Sensortechnik werden behandelt – im Interesse der Anwender zunächst gegliedert nach der zu messenden Größe. Erst im Anschluss daran sind die Inhalte entsprechend der verschiedenen Sensortypen strukturiert. Die 2., gründlich überarbeitete und aktualisierte Auflage wurde um die Themen akustische Sensoren, Zuverlässigkeit sowie drahtlose energieautarke Sensorsysteme ergänzt.

2012

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• Carl Hanser Verlag, page: 468
  Elektrische Messtechnik
  E. Schrüfer, L.M. Reindl, B. Zagar

Book chapters

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2018

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• Schrüfer E, Reindl L, Zagar B
  Elektrische Messtechnik: Messung elektrischer und nichtelektrischer Größen
  In: Elektrische Messtechnik: Messung elektrischer und nichtelektrischer Größen
  2018, Carl Hanser Verlag GmbH Co KG,

2016

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• D. Grgic, S. Böttcher, M. Pfeifer, J. Scherle, B. Völker, J. Burchard, S. Sester, L.M. Reindl
  Advanced Projects and Applications for Embedded Systems Engineering on E2LP Platform
  In: Embedded Engineering Education
  2016, Springer Verlag, pages: 119 - 132,
  » show abstract« hide abstract
  Abstract

  The E2LP-Platform is capable to impart many different fields of learning content. Starting from simple, short exercises also complex projects can be realized covering up to several weeks of workload. This work presents a documentation of four students projects developed and performed at University of Freiburg in the Advanced Embedded System Laboratory. This laboratory contains a dynamic classroom approach in which the required laboratory hardware is mobile. Exploring real-wold challenges and problems motivates the participants to acquire a deeper knowledge.

2015

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• H. Paul, J. Binder, H. Bäumel, Th. Kleckers, M. Horn, F. Höflinger
  Kapitel 9: Druck-, Kraft-, Drehmoment und Inertialsensoren
  In: Sensortechnik: Handbuch für Praxis und Wissenschaft
  2015, Springer Verlag,

2013

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• M. Freunek(Müller), U. Würfel, B. Zimmermann
  Photovoltaics in Micro Energy Harvesting
  In: Handbook of energy harvesting power supplies and applications
  2013, Pan Stanford Publishing, P. Spies [Hrg.], P. Spies [Hrg.], ISBN: 978-981-4241-86-1

2010

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• M. Freunek(Müller)
  Hocheffizient per Definition – Photovoltaik im Gebäude
  In: ep Photovoltaik 7-8
  2010, HUSS-MEDIEN, pages: 62 - 64,

2007

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• J. Wilde, L.M. Reindl, C. Stewart
  Einfluss von Design: Testing, Calibration, and Compensation
  In: Elsevier Compehensive Microsystems (Chapter 26)
  2007, Elsevier,

2005

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• L.M. Reindl, C.C.W. Ruppel
  Surface Acoustic Wave Delay Lines
  In: Wiley Encyclopedia of RF and Microwave Engineering, Vol. 6
  2005, Wiley, K. Chang, pages: 5012 - 5029, K. Chang,

2004

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• L.M. Reindl
  Rechnerunterstützte Messsysteme
  In: Elektrische Messtechnik
  2004, Hansa Verlag,

2002

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• R. Weigel, L.M. Reindl
  Wireless Communications and Sensing Based on Surface-Acoustic-Wave Devices
  In: Review of Radio Science 1999-2002
  2002, IEEE, pages: 413 - 426, ISBN: 0-471-26866-6
  » show abstract« hide abstract
  Abstract

  Surface-acoustic-wave (SAW) devices are special microwave components that have been used for electronic analog signal processing for over 30 years. A tremendous variety of devices and systems for consumer, commercial, and military applications has been developed, running now at an annual rate of some hundred million dollars. SAW filters, delay lines, and resonators play a key role in the radio-frequency (RF) and intermediate-frequency (IF) stages of many electronic systems, such as television sets, satellite receivers, remote control units, and mobile phones. The objective of this paper is to provide an overview of the latest developments in the SAW arena, and to identify novel emerging applications, especially for wireless communications and sensing. The pertinent key issues for the successful design and mass fabrication of SAW devices are addressed, and the underlying operating principles are discussed.

1988

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• H.P. Graßl, L.M. Reindl, H.-W. Wörz
  State-of-the-art elastic SAW convolvers
  In: Recent Developments in Surface Acoustic Waves
  1988, Springer-Verlag, D. F. Parker, G. A. Maugin, pages: 2 - 13, D. F. Parker, G. A. Maugin,

Talks

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2015

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• F. Höflinger, T. Ostertag
  Einladung als Experte für Impulsreferat zum Arbeitsthema „Technische Möglichkeiten zur Ortung von Tieren im Stall“
  2015 Fachgespräch „Tierortung im Stall“, Kuratorium für Technik und Bauwesen in der Landwirtschaft gemeinsam mit der Bayerischen Landesanstalt für Landwirtschaft, Grub, Germany

2011

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• A. Yousaf, F.A. Khan, L.M. Reindl
  Passive Wireless Sensing of Micro Coil Parameters in Fluidic Environment
  2011 Eurosensor 2011 Sept 4-7, Athen, Greece
• J.-M. Boccard, L.M. Reindl
  360° wireless interrogation concept for industrial torque measurements with SAW resonators
  2011 Proc. of EEEfcom - Workshop - Electrical and Electronic Engineering for communication, Ulm, Germany

Conference papers

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2019

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• Höflinger F, Bordoy J, Zhang R, Quan Y, Bannoura A, Simon N, Reindl L, Schindelhauer C, Wang Z
  Indoor Localization System Using Ultra Low-Power Radio Landmarks Based on Radio Signal Strength and Travel Time
  2019 Springer International Publishing, pages: 98 - 117
  » show abstract« hide abstract
  Abstract

  In this paper we present a novel indoor localization system to track the emergency responders using landmarks network. The low-power landmarks are small and cost-efficient and can be integrated into the building infrastructure, such as smoke detectors with very long operation duration thanks to radio wake-up technology. During the sleep mode the landmarks consumes only 66 {\$}{\$}{\backslash}upmu {\$}{\$}W and can maintain its operation up to 5 years. The positioning is achieved by combining the either the radio strength or UWB travel time and IMU based dead reckoning to overcome the disadvantages such as error due to multipath propagation and sensor drift. The experimental results show that the proposed system using either radio strength or radio travel time based ranging is able to outperform both standalone systems and meanwhile maintain the low power consumption.
• Hoeflinger F, Saphala A, Schott D J, Reindl L M, Schindelhauer C
  Passive Indoor-Localization using Echoes of Ultrasound Signals
  2019 2019 International Conference on Advanced Information Technologies (ICAIT) , pages: 60 - 65
• Laufer B, Krueger-Ziolek S, Docherty P D, Hoeflinger F, Reindl L, Moeller K
  Tidal volume via circumferences of the upper body: a pilot study
  2019 , pages: 3559 - 3562

2018

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• Dominik Jan Schott, Muhammad Faisal, Fabian Höflinger, Leonhard M Reindl
  A Multichannel Acoustic Chirp-Spread Modulation Approach Towards Diver-to-Diver Communication
  2018 Hammamet, Tunesien 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD), IEEE, pages: 475 - 479
  » show abstract« hide abstract
  Abstract

  In this work, we propose a single and multiband chirp signals for communication in the air and underwater channel. A Raspberry Pi based transceiver system and MATLAB are used for the demodulation of the chirp signals. The experiments, for both air and water, are conducted in static conditions, that is the transmitter and receiver are fixed. To increase the efficiency of signal processing, down-conversion or bandpass sampling is implemented on the receiver side. We use transmission bands between 60~kHz and 70kHz to reduce the impact of divers' communication on the maritime ecosystem and its natural communication bands. The structure of the demodulation is discussed in detail with focus on the frame detection and decision algorithm. In several different settings, we demonstrate the performance of this approach and transmit data of up to 12 Byte with data rates of 100 and 200 bit/s over 0.25 m in air and 4.5 m in water inside a highly echoic environment.
  
  
   
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• Schott DJ, Faisal M, Hoeflinger F, Reindl LM
  A Multichannel Acoustic Chirp-Spread Modulation Approach Towards Diver-to-Diver Communication
  2018 , pages: 475 - 479
• Reimer J, Stoecklin S, Reindl L
  Autonomous Low-PowerWireless Universal Sensor Module with a Custom Pulse Amplitude Modulated Chlorophyll Fluorometer
  2018 , pages: 1 - 4
• Schindelhauer C, Höflinger F, Bordoy J, Zhang R, Bannoura A, Reindl L, Simon N
  Localization System based on Ultra Low-power Radio Landmarks
  2018 7th International Conference on Sensor Networks , pages: 51 - 59
• Shi D, Reindl L
  Respiration Detection for Searching Trapped Victims using Small-Size UHF UWB Antenna
  2018 , pages: 1 - 3
• Schindelhauer C, Gavrikov P, Verboket P, Ungan T, Muller M, Lai M, Reindl L, Wendt T
  Using Bluetooth Low Energy to trigger an ultra-low power FSK wake-up receiver
  2018 25th International Conference on Electronics, Circuits and Systems , pages: 781 - 784

2017

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• Dominik Jan Schott, Muhammad Faisal, Fabian Höflinger, Leonhard M. Reindl, Joan Bordoy, Christian Schindelhauer
  Underwater localization utilizing a modified acoustic indoor tracking system
  2017 IEEE 7th International Conference on Underwater System Technology: Theory and Applications (USYS), Kuala Lumpur 2017 IEEE 7th International Conference on Underwater System Technology: Theory and Applications (USYS), pages: 1 - 5
  » show abstract« hide abstract
  Abstract

  We present a modified indoor localization system and the research into localization of divers utilizing acoustic chirp signals. The ASSIST infrastructure is used, which implements TCP/IP-based time synchronization for receiver nodes, timestamping of received chirps and server-side localization. Modifications of the original system are shown, as the transmission of signals at higher frequency and operation with high impedance transducers for the water channel. The results of position measurements in an indoor test pool as well as a small lake are shown to verify the systems functionality and investigate different multipath environments.
  
  
   
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• Dominik Jan Schott, Fabian Höflinger, Hai Yang, Rui Zhang, Leonhard M. Reindl
  Fuzzy inference system assisted inertial localization system
  2017 International Conference on Engineering, Technology and Innovation (ICE/ITMC), Funchal, Portugal 2017 International Conference on Engineering, Technology and Innovation (ICE/ITMC), pages: 89 - 93
  » show abstract« hide abstract
  Abstract

  In this paper we present a novel IMU (Inertial Measurement Unit) based indoor localization system assisted by a fuzzy inference system (FIS). The positioning is achieved by simply applying double integration to the acceleration data. And the accumulative position errors are eliminated by using FIS based acceleration restriction. In this way, the system can be used for general cases without any scenario and condition limitations. By considering smartphone as the IMU, it is also possible to realize applications such as navigation in the supermarket or guiding blind people through buildings. Indoor experiment has been carried out to verify the benefit of FIS based acceleration restriction. The experimental results show that the proposed new system is able to follow the true trajectory and achieve a tracking accuracy improvement of 84% in comparison to the one without FIS based acceleration restriction.
  
  
   
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• Ivo Häring, Johannes Scheidereiter, Stefan Ebenhöch, Dominik Jan Schott, Leonhard M. Reindl, Sven Köhler, Joan Bordoy, Christian Schindelhauer, Hermann Scheithauer, Sven Kaufmann
  Analytical engineering process to identify, assess and improve technical resilience capabilities
  2017 European Safety and Reliability Conference (ESREL 2017), Portorož, Slovenia Safety and Reliability – Theory and Applications, CRC Press, London, pages: 1069 - 1087
  » show abstract« hide abstract
  Abstract

  Reliability, risk control and more recently resilience enhancement are generally agreed to be of major interest for designing and improving technical and socio technical systems. However, for resilience enhancement of technical systems, the question arises how to achieve this aim in a systematic way. The present approach addresses the control of potentially disruptive events for an indoor logistics ultrasonic system, which can be used for locating goods or robots within storage or production halls. It is shown how to address in a systematic analytical process potentially disruptive events and how to generate scenarios for further detailed resilience analyses and evaluation. The scenarios are designed and assessed in such a way that technical requirements for increasing the resilience of the system can be derived. The paper describes the process in 8 steps: (1) system and context definition, (2) identification of system performance functions and related quantities, especially in undisturbed operation mode, (3) identification of potentially disruptive events and threats, (4) identification of critical combinations of disruptions and performance functions, e.g. using a resilience criticality matrix of combinations of performance functions and disruptions, (5) definitions of scenarios for detailed resilience assessment, (6) resilience assessment and analysis, (7) resilience evaluation, and (8) selection and implementation of design improvements. In addition, the paper exemplarily shows how such a resilience cycle informed process can be implemented and tailored for indoor logistic example.
  
  
   
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• F. Wolling, Ph. M. Scholl, L. M. Reindl, K. Van Laerhoven
  Combining capacitive coupling with conductive clothes: towards resource-efficient wearable communication
  2017 ACM International Symposium on Wearable Computers, Maui, Hawaii , pages: 146 - 149
  » show abstract« hide abstract
  Abstract

  Traditional intra-body communication approaches mostly rely on either fixed cable joints embedded in clothing, or on wireless radio transmission that tends to reach beyond the body. Situated between these approaches is body-coupled communication, a promising yet less-explored method that transmits information across the user's skin. We propose a novel body-coupled communication approach that simplifies the physical layer of data transmission via capacitive coupling between wearable systems with conductive fabrics: This layer provides a stable reference potential for the feedback path in proximity to the attached wearables on the human body, to cancel the erratic dependency on the environmental ground, and to increase the communications' reliability. Evaluation of our prototype shows significant increases in signal quality, due to reduced attenuation and noise. Requirements on hardware and, subsequently, energy consumption, cost, and implementation effort are reduced as well.
• D. Shi, T. Aftab, A. Yousaf, L. M. Reindl
  Design of a small size biquad-UWB-patch-antenna and signal processing for detecting respiration of trapped victims
  2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL)
  » show abstract« hide abstract
  Abstract

  In this contribution, we present an initial design of a small size Ultra-Wide-Band (UWB) antenna, which would be used as part of a semiautonomous flying platform for urban rescue of trapped victims. The antenna performance is experimentally investigated by conducting Step-Frequency-Continuous-Wave (SFCW) RADAR interrogation on a breathing human test subject. Measurements, made through a variety of common rubble materials further validate the system under development.

2016

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• A. Bannoura, L. Reindl, C. Schindelhauer
  Convergecast Algorithms for Wake-up Transceivers
  2016 The 5th International conference on Sensor Networks, Rome, Italy
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  Abstract

  New transceiver and receiver hardware technology allow the usage of special wake-up signals, which are able to awake neighbored sensor nodes from the sleep. However, such messages need more energy ew than those standard message transmissions em, when nodes are awake. Furthermore, the distance range rw is also smaller than the distance range rm of standard messages. Therefore, it does not completely replace duty-cycling for the convergecast problem in wireless sensor networks. We present a theoretical and practical discussion of energyefficient algorithms for the convergecast problem. First, we present a model based on the current technology and show that without constraints on the delivery times wake-up signals are obsolete, when arbitrary long sleeping times are allowed. The wake-up graph Gw and the message graph Gm are modeled by planar rwand rm-disk-graphs. Then, we give a competitive analysis for the general case, where we discuss an online D-convergecast algorithms bounded by competitive energy ratios. Finally, we present simulation results for these algorithmic ideas in the plane by considering the energy efficiency and the latency of data delivery.
• S. Stöcklin, A. Yousaf, L. Reindl
  Adaptive Elektronik zur effizienten drahtlosen Energieversorgung biomedizinischer Implantate
  2016 18. GMA/ITG Fachtagung Sensoren und Messysteme, Nürnberg, Germany
• C. Bentler, S. Stöcklin, T. Stieglitz
  Blueprint for implantable Brain Computer Interfaces made of commercial off-the-shelf components
  2016 NANS- NIC Joint Meeting, Baltimore, USA
• F.A. Khan, A. Yousaf, L.M. Reindl
  Build-Up Detection and Level Monitoring by Using Capacitive Glocal Technique
  2016 30th European Frequency and Time Forum (EFTF'16), York, United Kingdom
• F.A. Khan, R. Zhang, A. Yousaf, L.M. Reindl
  Design and FEM analysis of multi segment capacitive level sensor based on local and global E-fields
  2016 13th International Multi-Conference on Systems, Signals and Devices (SSD’16), Leipzig, Germany
• J. Kokert, T. Beckedahl, L.M. Reindl
  Development and Evaluation of a Modular Energy Management Construction Kit
  2016 Proceedings 18. GMA-ITG-Fachtagung, Nürnberg, Germany
• T. Kumberg, T. Beckedahl, L. M. Reindl
  Development and Evaluation of a Modular Energy Management Construction Kit
  2016 Proceedings 18. GMA-ITG-Fachtagung, Nürnberg, Germany
• T. Kumberg, J. Kokert, L. M. Reindl
  Development of a Wireless low-power Sensor Node for low latency Sensor Networks using Wake-Up Receivers
  2016 Proceedings 11th Future Security Conference, Berlin, Germany
• S. Bhatia, H. Yang, R. Zhang, F. Höflinger, L. Reindl
  Development of an Analytical Method for IMU Calibration
  2016 Proc. Int. Multi-Conference on Systems, Signals & Devices (SSD) , pages: 131 - 135
• J. Kokert, T. Beckedahl, L. M. Reindl
  Evaluating micro-power management of solar energy harvesting using a novel modular platform
  2016 PowerMEMS Journal of Physics Conference Series, volume: 773, issue: 1, page: 012042
• J. Bordoy, J. Wendeberg, C. Schindelhauer, F. Höflinger, L. Reindl
  Exploiting ground reflection for robust 3D smartphone localization
  2016 Proceedings of International Conference on Indoor Positioning and Indoor Navigation (IPIN), Madrid, Spain
• D. Vössing, K. M. Gad, M. Graf, M. Kasemann
  Heterojunction Solar Cell with Titanium Dioxide Nanolayer with an Efficiency of 10.1%
  2016 43th IEEE Photovoltaic Specialists Conference , pages: 2536 - 2539
• H. Yang, R. Zhang, F. Höflinger, W. Li, L. Reindl
  Vibration Error Compensation for Mobile Vehicle using Strap-down Inertial Navigation System
  2016 Proc. Int. Multi-Conference on Systems, Signals & Devices (SSD) , pages: 401 - 405
• T. Kumberg, J. Kokert, V. Younesi, S. König, L. M. Reindl
  Wake-up transceivers for structural health monitoring of bridges. In SPIE Smart Structures and Materials+ Nondestructive Evaluation and Health Monitoring
  2016 SPIE Smart Structures and Materials International Society for Optics and Photonics, page: 98041S

2015

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• S. Stöcklin, A. Yousaf, T. Volk, L. Reindl
  A Maximum Efficiency Point Tracking System for Wireless Powering of Biomedical Implants
  2015 Eurosensors XXIX, Freiburg, Germany
• S. Stöcklin, T. Volk, A. Yousaf, L. Reindl
  A Programmable and Self-Adjusting Class E Amplifier for Efficient Wireless Powering of Biomedical Implants
  2015 37th Annual International Conference of the IEEE EMBS, Milano, Italy
• T. Aftab, A. Yousaf, T. Ostertag, L. M. Reindl
  A novel microwave reflector-antenna as a resonant wireless passive mechanical sensor
  2015 IEEE IFCS&EFTF Int'l Frequency Control Symposium & European Frequency & Time Forum, Denver, Colorado, USA from April 12-16
• T. Aftab, A. Yousaf, J. Hoppe, S. Stöcklin, T. Ostertag, L. M. Reindl
  A parallel plate dielectric resonator as a wireless passive strain sensor
  2015 IEEE Sensors Applications Symposium, April 13-15, Zadar Croatia
• M. Knapp, P. M. Jäger, W. Ruile, I. Bleyl, L. M. Reindl
  A refined method to determine the elastic constants of SiO2 thin films
  2015 IEEE International Ultrasonics Symposium , pages: 277 - 280
• M. Knapp, P. M. Jäger, G. Grünauer, G. Scheinbacher, I. Bleyl, L. M. Reindl
  Accurate determination of thin film properties using SAW differential delay lines
  2015 IEEE International Ultrasonics Symposium, pages: 1704 - 1707
• M. Reusch, Ph. Katus, K Holc, W. Pletschen, L. Kirste, V. Zuerbig, D. Iankov, L. Reindl, O. Ambacher, V. Lebedev
  Aluminium nitride membranes with embedded buried idt electrodes for novel flexural plate wave devices
  2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), Anchorage, AK, USA , pages: 1291 - 1294
  » show abstract« hide abstract
  Abstract

  Novel flexural plate wave resonators based on bilayer AlN membranes were fabricated and investigated with respect to their piezoelectric response and residual film stress. In the proposed device design, the interdigital transducers (IDTs) are embedded between two AlN films. Here, chromium and aluminum were evaluated as suitable materials for IDT. Using Cr is beneficial with respect to conventional microfabrication technology, whereas Al enhances overall device performance due to enhanced conductivity. Finally, the proof-of-concept Lamb wave resonators were fabricated and characterized by means of laser Doppler vibrometry.
  
  
   
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• J. Kokert, L.M. Reindl
  Behavior Model of DC-DC Converters and Batteries for Micro-Energy-Management Simulation
  2015 Proceedings 29. Eurosensors, Freiburg, Germany
• S. Stöcklin, T. Volk, A. Yousaf, J. Albesa, L.M.Reindl
  Efficient Inductive Powering of Brain Implanted Sensors
  2015 IEEE Sensors Applications Symposium, April 13-15, Zadar Croatia
• T. Kumberg, R. Tannhäuser, L. M. Reindl
  Entwicklung eines Multi-Antennen Wake-up Empfängers
  2015 MikroSystemTechnik
• K. M. Gad, D. Vössing, P. Balamou, D. Hiller, B. Stegemann, H. Angermann, M. Kasemann
  High quality tunneling oxides for passivated contacts and heterojunctions for high efficiency silicon solar cells
  2015 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), pages: 1 - 6
• N. Simon, J. Bordoy, F. Höflinger, J. Wendeberg, M. Schink, R. Tannhäuser, L. Reindl, C. Schindelhauer
  Indoor Localization System for Emergency Responders with Ultra Low-power Radio Landmarks
  2015 Proceedings of 2015 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)
• F. Höflinger, J. Bordoy, N. Simon, J. Wendeberg, L. Reindl, C. Schindelhauer
  Indoor-Localization System for Smart Phones
  2015 Proceedings of IEEE International Workshop on Measurements and Networking (M&N), Coimbra, Portugal
• T. Volk, S. Stöcklin, C. Bentler, J. Ordonez, S. Hussain, A. Yousaf, T. Stieglitz, L.M. Reindl
  Inductive micro-tunnel for an efficient power transfer
  2015 Eurosensors XXIX
• J. Vertens, F. Fischer, C. Heyde, F. Höflinger, R. Zhang, L. Reindl, A. Gollhofer
  Measuring Respiration and Heart Rate using Two Acceleration Sensors on a Fully Embedded Platform
  2015 Proceedings of International Congress on Sport Sciences Research and Technology Support (icSPORTS 2015), Lisbon, Portugal
• F. Höflinger, R. Zhang, T. Volk, E. Garea-Rodríguez, A. Yousaf, C. Schlumbohm, K. Krieglstein, L. M. Reindl
  Motion capture sensor to monitor movement patterns in animal models of disease
  2015 Proc. of 6th IEEE Latin American Symposium on Circuits and Systems (LASCAS 2015), Montevideo, Uruguay
• T. Volk, C. Bentler, A. Yousaf, S. Stöcklin, T. Stieglitz, L. M. Reindl
  Novel concept for a wireless and batteryless brain implant array
  2015 IEEE SSD 12th International Multi-Conference on Systems, Signals and Devices; IEEE SSD, Sfax, Tunisia
• A. Ens, J. Din, T. Aftab, A. Yousaf, L. Reindl
  Resotorque – Drahtlose Drehmomentmessung mittels dielektrischer Resonatoren
  2015 VDMA Workshop – Sensorik für Antriebssysteme, Frankfurt , pages: 1 - 10
• A. Ens, J. Bordoy, J. Wendeberg, F. Höflinger, L.M. Reindl
  Selbstkalibrierende Innenraum-Lokalisierung mittels Ultraschall
  2015 Proc. of Fachveranstaltung Cyber-Physical-Systems, Stuttgart, Germany
• A. Traub-Ens, J. Bordoy, J. Wendeberg, F. Höflinger, L. Reindl, C. Schindelhauer
  Selbstkalibrierendes Ultraschallsystem für die Lokalisierung mobiler Einheiten in der Intralogistik
  2015 Proc. of the Mikrosystemtechnik-Kongress 2015, Karlsruhe, Germany
• J. Bordoy, J. Wendeberg, C. Schindelhauer, L. Reindl
  Single Transceiver Device-Free Indoor Localization using Ultrasound Body Reflections and Walls
  2015 Proceedings of International Conference on Indoor Positioning and Indoor Navigation (IPIN), Banff, Canada
• J. Bordoy, F. Höflinger, J. Wendeberg, N. Simon, L. Reindl
  Smart Phone Localization System with High Accuracy for Blind Persons
  2015 Proceedings of International Conference on Indoor Positioning and Indoor Navigation (IPIN), Banff, Canada
• A. Ens, J. Bordoy, J. Wendeberg, L. Reindl, C. Schindelhauer
  Ultrasound Transmission System for TDOA Localization with Unsynchronized Beacons
  2015 Proceedings of the 17th International Conference on Sensors and Measurement Technology/ (SENSOR 2015), Germany
• T. Kumberg, R. Tannhäuser, L. M. Reindl
  Using antenna diversity to improve wake-up range and probability
  2015 PIERS Proceedings, Prague , volume: 2091
• T. Kumberg, R. Tannhäuser, L. Zimmermann, M. Schink, C. Schindelhauer, L. M. Reindl
  Wake-Up Transceivers for Monitoring Critical Infrastructure - A Prototype Overcoming Duty Cycling in Wireless Sensor Networks
  2015 International Conference on Performance-based and Life-cycle Structural Engineering Proceedings 10th Future Security Conference, Berlin, Germany
• T. Volk, A. Yousaf, J. Albesa, S. Stöcklin, L. M. Reindl
  Wireless Power Distribution System for Brain Implants
  2015 IEEE I2MTC, Pisa, Italy, 2015
• T. Kumberg, R. Tannhäuser, M. Schink, S. Schneid, S. König, C. Schindelhauer, L. M. Reindl
  Wireless wake-up sensor network for structural health monitoring of large-scale highway bridges
  2015 International Conference on Performance-based and Life-cycle Structural Engineering School of Civil Engineering, The University of Queensland, pages: 1393 - 1401

2014

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• F. Höflinger, J. Wendeberg, J. Hoppe, R. Zhang, A. Ens, L. M. Reindl, Christian Schindelhauer
  Acoustic Indoor-Localization System for Smart Phones
  2014 Proc. of International Multi-Conference on Systems, Signals and Devices (SSD 2014) Castelldefels-Barcelona, Spain
• T. Kumberg, R. Tannhäuser, G. U. Gamm, L. M. Reindl
  Energy improved wake-up strategy for wireless sensor networks
  2014 Sensors and Measuring Systems, Proceedings of 17. ITG/GMA Symposium , volume: 2091, pages: 1 - 6
• J.-M. Boccard, T. Aftab, J. Hoppe, A. Yousaf, R. Hütter, L. M. Reindl
  Far- Field passive temperature sensing up to 700 °C using a dielectric resonator
  2014 IEEE International Conference on Wireless for Space and Extreme Environments, Wisee, European Space Agency, ESTEC, Noordwijk (The Netherlands)
• A. Ens, L.M. Reindl
  High Resolution Ultrasound Localization System
  2014 Proc. of MicroTEC Südwest - Cluster Conference, Freiburg, Germany
• A. Ens, L. M. Reindl
  High Resolution Ultrasound Localization System
  2014 Integrationsplattform SSI 2014, Villingen-Schwenningen, Germany
• M. Knapp, P. M. Jäger, M. Hauser, U. Rösler, W. Ruile, G. Scheinbacher, M. Honal, I. Bleyl, L. M. Reindl
  Investigation of GeO2 thin film properties for improvement of temperature coefficient of frequency of SAW devices
  2014 European Frequency and Time Forum , pages: 270 - 273
• J. Kokert, S.M. Torres Delgado, L.M. Reindl
  Low-Cost Spectrometer to characterize light conditions for photovoltaic Energy-Harvesting
  2014 Proceedings 17. GMA-ITG-Fachtagung, Nürnberg, Germany,
• A. Ens, T. Janson, L. M. Reindl, C. Schindelhauer
  Low-Power Simplex Ultrasound Communication for Indoor Localization
  2014 22nd European Signal Processing Conference (EUSIPCO 2014), Lisbon, Portugal
• M. Kasemann, J. Kokert, S.M. Torres Delgado, K. Rühle, L. M. Reindl
  Monitoring of indoor light conditions for photovoltaic energy harvesting
  2014 Systems, Signals & Devices (SSD), 11th International Multi-Conference on
• J. Hoppe, J.-M. Boccard, T. Aftab, A. Yousaf, A. Ojha, T. Ostertag, L.M. Reindl
  Open parallel-plate dielectric resonator for passive torque sensing
  2014 Proc. of Multi-Conference on Systems, Signals & Devices (SSD), Barcelona (Spain) , volume: 1, issue: 5, pages: 11 - 14
  » show abstract« hide abstract
  Abstract

  This paper presents a novel torque sensing concept, based on resonant perturbation of an open parallel plate dielectric resonator. When torque is applied to the shaft, the air gap between the parallel plates fixed on a clamp system is changed, which in turn shifts the frequency of the dielectric resonator. Finite Element Method (FEM) simulations using HFSS (ANSYS®) and experimental results regarding the effects of air gap variation on the TE01δ mode in the 2–3 GHz range are presented to prove the sensing concept.
• A. Ens, T. Janson, L. M. Reindl, C. Schindelhauer
  Robust Multi-Carrier Frame Synchronization for Localization Systems with Ultrasound
  2014 Proceedings of the 18th International OFDM Workshop 2014 (InOWo’14), Kettwig, Germany
• F. Höflinger, G. U. Gamm, J. Albesa, L. M. Reindl,
  Smartphone remote control for home automation applications based on acoustic wake-up receivers
  2014 Proc. of International Instrumentation and Measurement Technology Conference (I2MTC14), Montevideo, Uruguay
• T. Volk, J. Albesa, S. Stöcklin, A. Yousaf, L. M. Reindl
  Theoretical Approach to Setup a Multi-Antenna System for Brain Implants
  2014 2ND IDAACS Symposium Wireless Systems; IEEE International Conferences on Intelligent Data Aquisition and Advanced Computing Systems: Technology and Applications (IDAACS WIRELESS 2014), Offenburg
  » show abstract« hide abstract
  Abstract

  Due to the progressive development, there is a significant demand of passively powered implants in biomedical research. Small dimensions make it possible to place the devices into inaccessible or critical positions. As consequence, the coupling factor between reader and implant antenna is slight. This work therefore provides a novel analysis of inductive coupled systems based on numerical methods for determining a proper coil configuration. Keywords: inductive coupling, wireless power transfer, three antenna systems, deep brain stimulation.
• J. Hempel, S. Anees, J. Wilde, L. Reindl
  Thermo-Mechanical Stress Investigation of Integrated SAW Strain Sensors
  2014 IEEE EuroSimE, Ghent, Belgium
• A. Ens, L. M. Reindl
  Ultraschall Kommunikationssystem für die Innenraum Lokalisierung
  2014 2. DEGA Workshop "Messtechnische Anwendungen von Ultraschall", Drübeck, Germany
• A. Ens, J.Bordoy, J. Wendeberg, L. M. Reindl, C. Schindelhauer
  Unsynchronized Ultrasound System for TDOA Localization
  2014 Proc. of International IEEE Conference on Indoor Positioning and Indoor Navigation (IPIN'2014), Busan, Korea
• Fischer S., Fröhlich B., Ivaturi A., Herter B., Wolf S., Krämer K.W., Richards B.S., Goldschmidt J.C.
  Upconverter Materials and Upconversion Solar Cell Devices: Simulation and Characterization with the Broad Solar Spectrum Illumination
  2014 SPIE Photonics West, OPTO, Proc. SPIE 8981, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices III, 89810B
• Fischer S., Ivaturi A., Fröhlich B., Rüdiger M., Richter A., Krämer K.W., Richards B.S., Goldschmidt J.C.
  Upconverter Silicon Solar Cell Devices for Efficient Utilization of Sub-Band-Gap Photons Under Concentrated Solar Radiation
  2014 Proceedings of 39th IEEE Photovoltaic Specialists Conferenece, Tampa, USA
• G. U. Gamm, S. Stöcklin, L. Reindl
  Wake-up receiver operating at 433 MHz 11th International Multi-Conference on Systems, Signals & Devices (SSD), Barcelona, Spain
  2014 11th International Multi-Conference on Systems, Signals & Devices (SSD), Barcelona, Spain
• A. Ens, L. M. Reindl
  Wide-band piezo-electric ultrasound transceiver matching
  2014 17. GMA/ITG-Fachtagung Sensoren und Messsysteme, Nürnberg, Germany
• T. Jörger, U. Gamm, F. Höflinger, L. M. Reindl
  Wireless distance estimation with low-power standard components in wireless sensor nodes
  2014 14th Mechatronics Forum International Conference, Karlstad, Sweden
  
   
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• J.-M. Boccard, J. Hoppe, T. Aftab, A. Yousaf, R. Hüutter, L. M. Reindl
  ZST dielectric resonator for far-field passive high temperature sensing
  2014 SAW Symposium, Vienna (Austria)

2013

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• Robert Tannhäuser, Jean-Michel Boccard, Dominik Jan Schott, Leonhard M. Reindl
  Wireless Sensor Networks using Robust Antenna Packages for Infrastructure Security
  2013 8th Future Security 2013. Security Research Conference, Berlin, Germany Security Research Conference "Future Security", Fraunhofer Verlag, pages: 368 - 374
  » show abstract« hide abstract
  Abstract

  A robust, high efficiency slot antenna integrated in the sensor packaging for a wake-up receiver working at 868 MHz is presented. The wake-up approach as well as a novel wireless sensor node architecture based on the ARM Cortex M3 is discussed. With the low power wake-up transceiver strategy the average sleep current could be reduced to only 3.0 uA. Resulting in a battery lifetime of 7 years with a BR2032 battery. Simulation and measurement data will be presented. In fiel-test more than 60 meter wake-up range could be demonstrated.
  
  
   
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• A. Nimo, D. Grgic, T. Ungan, L. M. Reindl
  A new family of passive wireless RF harvesters based on R-C-Quartz oscillators
  2013 43nd European Microwave Conference (EuMC), Nürnberg , pages: 511 - 514
• G. Grünauer, M. Mayer, M. Knapp, P. M. Jäger, T. Ebner, K. Wagner, H. J. Pesch
  Derivation of accurate tensor data of materials in SAW devices by solving a parameter identification problem using an enhanced eigenvalue analysis of an infinite array model
  2013 IEEE International Ultrasonics Symposium , pages: 1700 - 1703
• J. Hempel, J. Wilde, L. M. Reindl
  Effects of Residual Stress on Assembled SAW Strain Sensors
  2013 Proceedings of 33rd PIERS, Progress In Electromagnetics Research Symposium, Taipei,Taiwan , pages: 286 - 290
• F. Sayed, T. Aftab, M. Eker, D. Hohlfeld, E. Rudnyi, T. Bechtold, J. G. Korvink
  Enabling efficient design of Self-Supplied SSHI-circuit for Piezoelectric MEMS Energy Harvester
  2013 Mikrosystemtechnik Kongress, Aachen
  » show abstract« hide abstract
  Abstract

  In this work we apply a novel modeling methodology based on model order reduction for multi-physical microsystems to efficiently design an improved self-supplied synchronized switching on inductor (SSHI) circuit for MEMS piezoelectric energy harvesters. Output voltage and power were increased by 17% and 37% respectively.
• J. Kokert, M. Kasemann, L.M.Reindl
  Energy Resources for Wireless Sensor Nodes
  2013 Workshop on Renewable Energy Systems at York University, Toronto, Canada
• J. Kokert, F. Wolling, F. Höflinger, L.M. Reindl
  Improvements and Evaluation of the Indoor Laser Localization System GaLocate
  2013 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2013), Montbéliard, France
• R. Zhang, A. Bannoura, F. Höflinger, L.M. Reindl, C. Schindelhauer
  Indoor Localization Using A Smart Phone
  2013 Proc. of IEEE Sensors Applications Symposium (SAS 2013),Galveston, USA
• A. Ens, F. Höflinger, J. Wendeberg, L. M. Reindl, C. Schindelhauer
  Indoor Positioning using Ultrasonic Waves with CSS and FSK Modulation for Narrow Band Channel
  2013 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2013), Montbeliard, France
• R. Zeiser, S. Ayub, J. Hempel, M. Berndt, J. Wilde
  Mechanical Stress Analyses of Packaged Pressure Sensors for Very High Temperatures
  2013 46th International Symposium on Microelectronics IMAPS, Orlando
• A. Ens, A. Yousaf, T. Ostertag, L. M. Reindl
  Optimized Sinus Wave generation with Compressed Sensing for Radar Applications
  2013 Proc. of 2nd International Workshop on Compressed Sensing applied to Radar (CoSeRa'2013), Bonn, Germany
• Kasemann, Martin, Reindl, L M, Rühle, K
  Photovoltaic Energy Harvesting under Low Lighting Conditions
  2013 Proceedings of SENSOR 2013, pages: 483 - 485
• Kasemann, Martin, Rühle, Karola, Gad, Karim M, Glunz, Stefan W
  Photovoltaic energy harvesting for smart sensor systems
  2013 Proceedings of the SPIE Conference on Smart Sensors, Actuators, and MEMS VI, page: 87631T
• A. Ens, C. Zech, K. Becker, L. Georgi
  Radar Based Detection and Tracking of Objects under Poor Visibility Conditions
  2013 Proceedings of the 16th International Conference on Sensors and Measurement Technology (SENSOR 2013), Germany
• F. Sayed, T. Aftab, M. Eker, D. Hohlfeld, T. Bechtold, J. G. Korvink
  Reduced Order Modeling Enables System Level Simulation of a MEMS Piezoelectric Energy Harvester with a Self-Supplied SSHI-Scheme
  2013 IEEE International conference on Thermal, Mech. and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), Wroclaw, Poland
• J. Bordoy, P. Hornecker, F. Höflinger, J. Wendeberg, R. Zhang, C. Schindelhauer, L. Reindl
  Robust Tracking of a Mobile Receiver using Unsynchronized Time Differences of Arrival
  2013 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2013), Montbéliard, France,
• J. Hempel, D. Finke, M. Steiert, R. Zeiser, M. Berndt, J. Wilde, L.M. Reindl
  SAW Strain Sensors- High Precision Strain Sensitivity Investigation on Chip-Level
  2013 Joint UFFC, EFTF and PFM Symposium, Prague, Czech
• J. Hempel, S. Anees, E. Zukowski, M. Berndt, J. Wilde, L.M. Reindl
  STRAIN TRANSFER ANALYSIS OF INTEGRATED SURFACE ACOUSTIC WAVE SENSORS
  2013 ASME InterPACK, San Francisco,USA
• J.-M. Boccard, A. Bannoura, O. Gorgis, G.U. Gamm, L.M. Reindl
  Slot antenna packaging for infrastructure monitoring based on wake-up transceiver strategy
  2013 Proc. of ICWISE, IEEE Conference on Wireless Sensor, Kuching (Malaisia , volume: 84, issue: 89, pages: 2 - 4
  » show abstract« hide abstract
  Abstract

  The use of the package as a radiating element is the optimal solution in term of robustness for wireless sensor network (WSN) applications such as infrastructure monitoring. A robust, 83 % efficient and 6.5 dBi gain slot antenna packaging (simulation values in air) for wireless sensor nodes working at 868 MHz is presented in this paper. A low power wake-up radio transceiver strategy allowing a current consumption of 3.8 μA is associated to the radiating package. The theoretical battery life time for a 3 V input voltage and a 220 mA/h battery capacity is more than 6 years using the proposed system. Therefore the combination between the antenna packaging and wake-up approach increases the wireless system life time. Finite Element Method (FEM) simulation and experimental results are presented to show the effects of different concrete supports on the antenna performances. Moreover, indoor and outdoor wake-up rate measurements show the coverage efficiency of the complete device. Using a transmission power of +10 dBm and a wake-up sensitivity of -51.8 dBm, a distance of 55 meters is reached in comparison to more than 250 meters for data transmission.
• F. Sayed, T. Aftab, M. Eker, D. Hohlfeld, T. Bechtold, J. G. Korvink
  System Level Simulation of a Reduced Order Model for a MEMS Piezoelectric Energy Harvester with a Self- Supplied SECE-Circuit
  2013 6th ECCOMAS, Thematic Conference on Smart Structures and Materials (SMART2013), Politecnico di Torino, Italy
• A. Bannoura, C. Ortolf, C. Schindelhauer, L.M. Reindl
  The Wake Up Dominating Set Problem
  2013 9th International Symposium on Algorithms and Experiments for Sensor Systems, Wireless Networks and Distributed Robotics, Sophia Antipolis, France
• A. Ens, F. Höflinger, T. Jansen, J. Wendeberg, L.M. Reindl, C. Schindelhauer
  eCULTS: energy autacrtic Configuration-free Ultrasonic Tracking System
  2013 Proc. of MicroTEC Südwest - Cluster Conference, Stuttgart, Germany

2012

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• O. Abhishek, A. Yousaf, L.M Reindl
  Characterization of Dielectric Resonator as a Passive Wireless Sensing Element
  2012 ICST 2012, 6th International Conference on Sensing Technology, Kolkata, India
• J. Albesa, M. Gasulla
  Inductive Power Transfer for Autonomous Sensors in Presence of Metallic Structures
  2012 Proceedings of I2MTC 2012
• J. Albesa, M. Gasulla
  Voltage Regulation on Inductive Power Links for Autonomous Sensors
  2012 Proceedings of I2MTC 2012
• A. Nimo, D. Grgic, L.M. Reindl
  Ambient Electromagnetic wireless energy harvesting using multiband planar antenna, Systems, Signals and Devices (SSD)
  2012 9th International Multi-Conference , pages: 1 - 6
• F. Höflinger, J. Müller, M. Törk, L.M. Reindl, W. Burgard
  A Wireless Micro Inertial Measurement Unit (IMU)
  2012 Proc. of International Instrumentation and Measurement Technology Conference (12MTC12), Graz, Austria
• J. Hoppe, F. Höflinger, L.M. Reindl
  Acoustic Receivers for Indoor Smartphone Localization
  2012 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2012), Sydney, Australia
• F. Höflinger, J. Wendeberg, R. Zhang, M. Bührer, J. Hoppe, A. Bannoura, L.M. Reindl, C. Schindelhauer
  Acoustic Self-calibrating System for Indoor Smartphone Tracking (ASSIST)
  2012 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2012), Sydney, Australia
• J. Hempel, E. Zukowski, M. Berndt, L.M. Reindl, J. Wilde
  Assembly of α-Quartz for Surface Acoustic Wave (SAW) Strain Gauges Application
  2012 4th IEEE-CPMT Electronics Systems Integration Technologies Conference - ESTC - Amsterdam, Netherland
  » show abstract« hide abstract
  Abstract

  In this paper a finite element (FE) model has been developed for the simulation of thermo-mechanical stress in the sensor substrate. The bond topology has been optimized with respect to bond material properties. Based on the simulations, experiments with two bond technologies and three bond materials were carried out. The effect of thermomechanical stress on an α-quartz sample, attached to a heattreatable steel carrier has been measured and evaluated with white-light interferometry. The bond quality has been evaluated with shear tests, thermal load cycle tests and microsections. The corresponding offset due to the remaining thermo-mechanical stress in the sensor substrate was measured and analyzed with a network analyzer. The investigated bond materials and technologies are providing low offset of the sensor signal and a high coupling of the measuring quantity into the SAW sensor.
• J.-M. Boccard, L.M. Reindl
  Ceramic and magnetic loop antennas for wireless interrogation of SAW Resonators on rotating machinery
  2012 Proc. of iWAT2012 - IEEE International Workshop on Antenna Technology, Tucson, USA
• K. Rühle, M. Freunek(Müller), L.M. Reindl, M. Kasemann
  Designing photovoltaic cells for indoor energy harvesting systems
  2012 Proc. International Multi-Conference on Systems, Signals and Devices (SSD) 9, Chemnitz, Germany , pages: 1 - 5
• Heinrich, M, Hidayat, H, Hameiri, Z, Hoex, B, Aberle, AG
  Dopant profiles of laser-doped multicrystalline silicon wafers from electrochemical capacitance-voltage measurements
  2012 Proceedings of the 27th European Photovoltaic Solar Energy Conference, Frankfurt, Germany
• Rühle, Karola, Reindl, Leonhard M., Kasemann, Martin
  Energy Capture with Optimized Photovoltaic Cells under Low Lighting Conditions
  2012 Proceedings of the IEEE International Conference on Green Computing and Communications, pages: 628 - 630
• A. Nimo, D. Grgic, L.M. Reindl
  Impedance optimization of wireless electromagnetic energy harvesters for maximum output efficiency at µW input power
  2012 Active and Passive Smart Structures and Integrated Systems 2012, volume: 8341
  » show abstract« hide abstract
  Abstract

  This work presents the optimization of radio frequency (RF) to direct current (DC) circuits using Schottky diodes forremote wireless energy harvesting applications. Since different applications require different wireless RF to DC circuits, RF harvesters are presented for different applications. Analytical parameters influencing the sensitivity and efficiency of the circuits are presented. Results showed in this report are analytical, simulated and measured. The presented circuits operate around the frequency 434 MHz. The result of an L-matched RF to DC circuit operates at a maximum efficiency of 27 % at-35 dBm input. The result of a voltage multiplier achieves an open circuit voltage of 6 V at 0 dBm input. Theresult of a broadband circuit with a frequency band of 300 MHz, achieves an average efficiency of 5 % at -30 dBm and open circuit voltage of 47 mV. A high quality factor (Q) circuit is also realized with a PI network matching for narrow band applications.
• J. Kokert, F. Höflinger, L.M. Reindl
  Indoor Localization System based on Galvanometer-Laser-Scanning for numerous Mobile Tags (GaLocate)
  2012 Proc. of International Conference on Indoor Positioning and Indoor Navigation (IPIN'2012), Sydney, Australia
• F. Höflinger, R. Zhang, L.M. Reindl
  Indoor-localization System Using a Micro Inertial Measurement Unit (IMU)
  2012 Proc. of 2012 International Conference on EUROPEAN FREQUENCY AND TIME FORUM (EFTF2012), Gothenburg, Sweden
• G.U. Gamm, L.M. Reindl
  Intelligent meter readout by use of wake-up receivers
  2012 Proc. of Micro Alliance Symposium , Freiburg, Germany
• A. Yousaf, F. Höflinger, L.M. Reindl
  Loosely Coupled Transformer Based Wireless Sensing of Open Loop Micro Coils
  2012 Proc. of European Frequency and Time Forum (EFTF2012), Gothenburg, Sweden
• A.Yousaf, L.M Reindl
  Loosely coupled transformer based wireless sensing of resonators
  2012 Proc. Of European Frequency and time forum EFTF
• J.-M. Boccard, L.M. Reindl
  Printed loop and ceramic antenna for wireless interrogation of SAW resonators on a clamp system
  2012 Proc. of SSD2012 - IEEE International Conference on Systems, Signals and Devices, Chemnitz, Germany
• G.U. Gamm, L.M. Reindl
  Range extension for wireless wake-up receivers
  2012 Proc. IEEE International Conference on Sensors, Circuits and Instrumentation Sys- tems 2012 (SSD-12) , Chemnitz, Germany
• J.-M. Boccard, L.M. Reindl
  SSI TorqueSENS: Ceramic Antennas for Wireless Interrogation of SAW Resonators
  2012 Proc. of MicroTEC Südwest - Cluster Conference, Stuttgart, Germany
• M. Erd, M, M. Kostic, A. Stolz, F. Schaefer, C. Brenneis, T. Ostertag, M. Loschonsky, L. M. Reindl
  Self-synchronized energy efficient event detection with wireless sensor networks
  2012 9th International Multi-Conference on Systems, Signals and Devices (SSD),
  » show abstract« hide abstract
  Abstract

  The presented work aims at development of a management evaluation system (condition monitoring) in the event of an explosion using a network of wireless sensors. The flow of information in the situation assessment system is made possible with the applied energy autonomous and energy-efficient wireless sensor nodes. Through this evaluation system, we will be able to do a real time assessment on the state of the damaged infrastructure through which we will be able to react to the situation in the area in a timely manner. We will show a new wireless sensor network topology and develop new rules for self-synchronization for energy efficient and collision free communication which is capable of data transmission in the event of an emergency situation.
• G.U. Gamm, L.M. Reindl
  Smart metering using distributed wake-up receivers
  2012 Proc. IEEE International Instrumentation and Measurement Technology Conference (I2MTC12) , Graz, Austria
• Q. Hamp, L.M. Reindl
  Soft robot concept for autonomous propagation in confined and obstructed environments
  2012 IEEE International Symposium on Safety, Security and Rescue Robotics, College Station, TX, USA
• R. Zhang, F. Höflinger, L.M. Reindl
  TDOA based Localization using Interacting Multiple Model Estimator and Ultrasonic Transmitter/Receiver
  2012 Proc. of 2012 International Multi-Conference on Systems, Signals and Devices (SSD2012), Chemnitz, Germany
• K. Rühle, M. Freunek, L.M. Reindl, M. Kasemann
  Towards New Design Rules for Indoor Photovoltaic Cells
  2012 Systems, Signals and Devices (SSD), 2012 9th International Multi-Conference on , pages: 1 - 5
  » show abstract« hide abstract
  Abstract

  Recent research focuses on developing photovoltaic cells that are optimized for indoor conditions and therefore suitable for photovoltaic energy harvesting in micro systems. The available conditions for indoor photovoltaic cells are investigated and discussed concerning intensity and spectra. The influence of the parallel and series resistances on the efficiency of crystalline and amorphous Silicon devices with decreasing intensity are discussed and compared to simulations with the two diode model. For low intensities as present indoors (<; 1 mW cm-2) the parallel resistance restricts the achievable efficiency and needs therefore to be optimized.
• K. Rühle, S.W. Glunz, M. Kasemann
  Towards new design rules for indoor photovoltaic cells
  2012 38th IEEE Photovoltaic Specialists Conference (PVSC), Austin, TX, USA , pages: 002588 - 002591
  » show abstract« hide abstract
  Abstract

  The common design rules for outdoor solar cells do not apply necessarily for indoor photovoltaic cells due to differences in spectra and intensities. Since no general standard for indoor conditions is currently available, the first aim of this paper is to present a statistical approach encompassing the diversity of available intensities and spectra which shall enable a systematic derivation of a standard for indoor conditions. In a second step, the influences of injection-and spectra-dependent parameters on cell efficiencies are studied with the focus on indoor conditions. It is shown that the parallel resistance has to be increased above 50 kΩcm2 in order to achieve an efficiency above 10% at intensities below 10−3 W/cm2 (∼0.01 suns). The influence of the series resistance is negligible in this intensity range, allowing values in the order of 10 Ωcm2 without appreciable efficiency reduction. This gives room for wider design variations with respect to base and emitter doping, optimization of bulk-, surface- and emitter recombination, contact optimization and back contact cell designs. The combined evaluation of possible photovoltaic cell parameters show that efficiencies of more than 10% at intensities as low as 10−4 W/cm2 are accessible.
• G.U. Gamm, T. Ungan, L.M. Reindl
  Using quartz resonators for maximizing wake-up range in wireless wake-up receivers
  2012 Proc. of European Frequencyand Time Forum (EFTF2012) , Gothenburg, Sweden
• A.Yousaf, L.M Reindl
  Wireless Impedance Spectroscopy of passive elements using Anti-Helmholtz coil pair
  2012 Proc. of IWIS 2012 – International conference on Impedance Spectroscopy, Chemnitz, Germany
• A.Yousaf, L.M Reindl
  Wireless sensing of Open loop micro coils using an air core Helical coil
  2012 Proc. of SSD2012 - IEEE International Conference on Systems, Signals and Devices, Chemnitz, Germany

2011

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• A. Yousaf, F.A. Khan, L.M. Reindl
  Analytical Modeling and Simulation of inductively coupled Passive Sensors
  2011 International Conference on Advanced Modeling and Simulation ICAMS, Islamabad, Pakistan
• J.Albesa, M.Gasulla
  Seat Occupancy and Belt Detection in Removable Seats via Inductive Coupling
  2011 Proceedings of IEEE Vehicular Technology Conference, VTC-Fall 2011
• G. Bruckner, T. Aubert, J. Bardong, D. Eisele, R. Fachberger, E. Mayer, S. Salzmann
  Investigations of Several Langasite Cuts by High Temperature in situ Characterizations of Surface Acoustic Waves Delay Lines
  2011 Proceeding Eurosensors XXV, September 4-7, Athens, Greece , pages: 317 - 320
• E. Forsén, D. Nilsson, S. Ballandras, E. Mayer, S. Sakharov
  Jet-and-Flash Nano Imprint Lithography: Fabrication of Passive Wireless Surface Acoustic Wave Sensors
  2011 Proceeding Eurosensors XXV, September 4-7, Athens, Greece , pages: 860 - 863
• D. Richter, H. Fritze, S. Sakharov, E. Forsén, E. Mayer, L.M. Reindl
  Thin Film Electrodes for High Temperature Surface Acoustic Wave Devices
  2011 Proceeding Eurosensors XXV, September 4-7, Athens, Greece , pages: 168 - 171
• J. Albesa, T. Jäger, L.M. Reind, M.Gasulla
  Wireless Power transmission for Autonomous Sensors in Removable Vehicle Seats
  2011 Proceedings of IEEE Vehicular Technology Conference, VTC-Fall 2011
• Heinrich, M, Palina, N, Wong, J, Hoex, B, Aberle, A
  Accurate measurement of laser-doped line sheet resistance for silicon wafer solar cell applications
  2011 Technical Digest 21st International Photovoltaic Science and Engineering Conference, Fukuoka, Japan
• M. Kasemann, L.M. Reindl, B. Michl, W. Warta, A. Schütt, J. Carstensen
  All-Contactless Measurement of Series Resistance Distributions on Solar Cells with Photoluminescence Imaging
  2011 San Jose, CA, USA
• J. Wendeberg, F. Höflinger, C. Schindelhauer, L.M. Reindl
  Anchor-free TDOA Self-Localization
  2011 Guimarães, Portugal Proc. of 2011 International Conference on Indoor Positioning and Indoor Navigation (IPIN'2011)
• A. Yousaf, F.A. Khan, L.M. Reindl
  Contactless Passive Sensor System for Measuring Micro Inductors
  2011 Proc. of RadioTecC - Workshop - Radio Techniques and Technologies for Commercial Communication and Sensing Applications, Berlin, Germany
• A. Nimo, D. Grgic, L.M. Reindl
  Electrically small Planner Antenna for Compact Electromagnetic (EM) Wireless energy harvester
  2011 Proc. Power MEMS 2011, pages: 310 - 313
  » show abstract« hide abstract
  Abstract

  This work presents the optimization of antenna captured low power radio frequency (RF) to direct current (DC) power converters using Schottky diodes for powering remote wireless sensors. Linearized models using scattering parameters show that an antenna and a matched diode rectifier can be described as a form of coupled resonator with different individual resonator properties. The analytical models show that the maximum voltage gain of the coupled resonators is mainly related to the antenna, diode and load (remote sensor) resistances at matched conditions or resonance. The analytical models were verified with experimental results. Different passive wireless RF power harvesters offering high selectivity, broadband response and high voltage sensitivity are presented. Measured results show that with an optimal resistance of antenna and diode, it is possible to achieve high RF to DC voltage sensitivity of 0.5 V and efficiency of 20% at −30 dBm antenna input power. Additionally, a wireless harvester (rectenna) is built and tested for receiving range performance.
• G.U. Gamm, L.M. Reindl
  Energiesparsamer Funksensorknoten mit Echtzeitverhalten
  2011 Proc. of EEEfCom - Workshop Hochfrequenzelektronik, Ulm, Germany
• R. Zeiser, T. Jörger, T. Fellner, J. Wilde
  Entwicklung von kapazitiven Dehnungsmessstreifen in Dünnschichttechnologie für drahtlose, intelligente Systeme
  2011 MikroSystemTechnik - KONGRESS, Darmstadt, Deutschland
• F. Höflinger, L.M. Reindl
  Erhöhung der Fahrsicherheit und die Erfassung des ökonomischen Fahrverhaltens im Busfernverkehr durch Onboard-Unit mit Inertialnavigationssystem (INS)
  2011 Proc. of EEEfCom - Workshop Hochfrequenzelektronik, Ulm, Germany
• F. Höflinger, A. Ojha, L.M. Reindl
  IMU based Onboard-Unit to measure the driveability of transport buses
  2011 Proc. of 5th International Conference on Sensing Technology (ICST2011), Palmerston North, New Zealand
• R. Zhang, F. Höflinger, O. Gorgis, L.M. Reindl
  Indoor Localization Using Inertial Sensors and Ultrasonic Rangefinder
  2011 Proc. of 2011 International Conference on Wireless Communications & Signal Processing (WCSP'2011), Nanjing, China
• F. Höflinger, L.M. Reindl
  Indoor-Lokalisierungssysteme für den Einsatz in der Intralogistik
  2011 Berlin, Germany Proc. of RadioTecC - Workshop Radio - Techniques and Technologies for Commercial Communication and Sensing Applications
• Q. Hamp, A. Kleiner, L.M. Reindl
  Lessons Learned from German Research for USAR
  2011 9th IEEE International Symposium on Safety, Security, and Rescue Robotics/Kyoto, Japan
• G.U. Gamm, M. Kostic, M. Sippel, L.M. Reindl
  Low power wireless sensor node for use in building automation
  2011 Proc. of 12th annual IEEE Wireless and Microwave Technology (WAMI) Conference (WAMICON’11), Clearwater (FL), USA
• F. Höflinger, L.M. Reindl
  Multiple device control via Wireless Access Numerous Destinations (WAND)-Pointer
  2011 Nottingham, United Kingdom Proc. Seventh International Conference on Intelligent Environment (IE'11)
• T. Fellner, J. Wilde, R. Zeiser, T. Jörger, M. Törk, L. Reindl
  Neuartige hochohmige Dünnschicht-Folien-DMS für Wireless Condition Monitoring
  2011 MikroSystemTechnik - KONGRESS, Darmstadt, Deutschland
• R. Zhang, L.M. Reindl
  Pedestrian motion based inertial sensor fusion by a modified complementary separate bias Kalman filter
  2011 IEEE Sensors Applications Symposium (SAS), San Antonio, USA, 2011, 209-213
• P.W. Ruch, G.I. Meijer, T. Brunschwiler, S. Paredes, W. Escher, M. Freunek(Müller), C.L. Ong, R. Ghannam, A. Khalil, B. Michel
  Recycling thermal energy boosts efficiencies in datacenters and concentrated photovoltaic systems
  2011 Smart Energy Strategies Conference, ETH Zurich
• A. Yousaf, L.M. Reindl
  Remote Sensing of micro coil parameters using Electrically small magnetic loop antenna
  2011 EEEfcom Electrical and Electronic Engineering for communication 25-26th May 2011 Ulm Germany
• Q. Hamp, R. Zhang, L. Chen, O. Gorgis, T. Ostertag, Y. Yankelevich, J. Pavlina, M. Loschonsky, F. Schilling, L.M. Reindl
  Results from German research project I-LOV
  2011 Proceedings of International Conference on Wireless Technologies for Humanitarian Relief. (ACWR2011), India Proceedings of International Conference on Wireless Technologies for Humanitarian Relief. (ACWR2011)
• E. Mayer, D. Eisele, L.M. Reindl, V. Plessky, D. Richter, H. Fritze
  SAW Parameters for Langasite att High Temperatures
  2011 1. Proceedings of 2011 IEEE International Ultrasonics Symposium, Orlando, Florida, USA
• Q. Hamp, L.M. Reindl
  Soft, self-propelled endoscope for minimally invasive interventions
  2011 Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik (DGBMT), VDE
• M. Freunek(Müller), W. Escher, R. Ghannam, J. Goicochea, B. Michel, C.L. Ong, S. Paredes
  Ultra-High- Concentration Photovoltaic -Thermal Systems based on Microfluidic Chip Coolers
  2011 7th International Conference on Concentrating Photovoltaic Systems CPV 7 AIP Conference Proceedings, volume: 1407, pages: 231 - 234
• C.L. On, W. Escher, R. Ghannam, J. Goicochea, A. Khalil, B. Michel, M. Müller, S. Paredes, P. Ruch
  Waste Heat Energy Re-use from High Concentration Photovoltaic (HCPV) Solar Cells for Saline and Brackish Water Desalination
  2011 TUM DeSal Conference 2011 on Desalination Systems with Transient Power Supply, Garching (München)
• F. Höflinger, R. Zhang, L.M. Reindl
  Wireless Access to Numerous Destinations (WAND)-Pointer for museums
  2011 Guimarães, Portugal Proc. of 2011 International Conference on Indoor Positioning and Indoor Navigation (IPIN'2011)
• A. Yousaf, T. Jäger, L.M. Reindl
  Wireless measurement of open loop micro coils parameters
  2011 28thIEEE International Instrumentation and measurement conference I2MTC Binjiang Hangzhou China
• A. Yousaf, T. Jäger, L.M. Reindl
  Wireless measurement system for characterizing open loop micro coils parameters
  2011 7th German Micro wave conference GeMIC Darmstadt

2010

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• E. Mayer, I. Shrena, D. Eisele, H. Wegert, J. Bardong, M. Schmitt, L.M. Reindl
  Characterization of SAW propagation in Langasite at HighTemperatures
  2010 SAW Symposium, Villach, Austria
• M. Akresh, L.M. Reindl
  Extended Measurement Range of Vortex Flow Meter in High Turbulent Range
  2010 FLOMEKO Taipei Taiwan , page: 68
• T. Maser, L.M. Reindl, D. Benyoucef
  Adaptiver Differentiator mit gefilterter Referenz
  2010 Sensoren und Messsysteme, Nürnberg, Germany
• L. Chen, M. Loschonsky, L.M. Reindl
  Characterization of Delay Spread for Mobile Radio Communications under Collapsed Buildings
  2010 IEEE Int. symp. on personal, indoor and mobile radio communications (PIMRC)
• Q. Hamp, L.M. Reindl
  Decision behaviour during Urban Search and Rescue: A German case study
  2010 Search and Rescue, Shepard, Aberdeen, UK
• T. Becker, B.-S. Lee, Q. Hamp, M. Eitelberg
  Efficient Decision Support for Crisis Management Based on Information Fusion and Modern SOP Algorithms
  2010 Proceedings Informatik, Technical Reports, GI-Edition, Leipzig, Germany
• G.U. Gamm, L.M. Reindl
  Energieeffiziente Funksensorknoten durch den Einsatz von Wake-Up Receivern
  2010 Proc. of EEEfCom - Workshop Hochfrequenzelektronik, Ulm, Germany
• M. Törk, A. Lastochkin, T. Jäger, L.M. Reindl
  Energy Harvesting Demonstration System Supplied By Pressurized Air
  2010 Como, Italy Proc. of Int. conf. on smart systems integration
• D. Eisele, H. Wegert, I. Shrena, J. Bardong, L. M. Reindl
  Entwicklung eines Hochtemperaturmessaufbaus zur Bestimmung der akustischen Parameter von Hochfrequenz-OFW-Bauteilen
  2010 Sensoren und Messsysteme 2010, Nürnberg
• M. Akresh, L.M. Reindl
  Entwurf und Aufbau einer Auswerteelektronik zur Optimierung eines Vortex-Durchflussmesssystems
  2010 Nürnberg, 18-19 Mai 2010 ITG- Sensoren und Messsysteme
  » show abstract« hide abstract
  Abstract

  Das Vortex-Durchflussmesssystem wird in zahlreichen Industriezweigen zur Messung des Volumenstroms von Flüssigkeiten, Gasen und Dampf eingesetzt. Das System arbeitet nach dem Prinzip der Wirbelablösung, welche auch als „kàrmànsches Phänomen“ bekannt ist. Das Vortex-Messprinzip hat den Nachteil, dass nur bis zu einer bestimmten Strömungsgeschwindigkeit eine gleichmäßige Wirbelablösung in der kàrmànschen Wirbelstrasse vorliegt. Oberhalb dieser maximalen Strömung entstehen zusätzliche Verwirbelungen (chaotischer Bereich) im Strömungskanal, welche die Erkennung des tatsächlichen Wirbels erschweren. Für den Anwender eines Strömungsmessgerätes ist es wichtig, dass das eingesetzte Messgerät auch außerhalb des Messbereiches noch plausible Messsignale ausgibt. Im Rahmen dieser Arbeit wurde untersucht, in wie weit der Arbeitsbereich von Vortex-Durchflussmesssystemen in den chaotischen Bereich ausgedehnt werden kann. Der Schwerpunkt dieser Arbeit liegt im Entwurf und Aufbau einer Auswertelektronik, mit der eine Durchflussmessung nach dem Prinzip der kàrmànschen Wirbelstraße möglich ist. Dabei wurde ein typischer Durchflussmesser mit Messbereich von 0,5 bis 4,5 l/min außerhalb des Messbereichendes (>4.5 l/min) mit klassischen Signalverarbeitungsmethoden analysiert und ausgewertet.
• M. Akresh, W. Walker, L.M. Reindl
  Flow Measurement using Kalman Filter for Smoothing Vortex Shedding Frequency
  2010 Austin, USA, May 3-6 2010 IEEE International Instrumentation and Measurement Technology Conference, pages: 234 - 237
• Q. Hamp, M. Eitelberg, B.-S. Lee, T. Becker, D. Wiebeck, L.M. Reindl
  Fusion von Informationen bei Ortungs- und Bergungseinsätzen
  2010 Proceedings 15. ITG-/GMA-Fachtagung Sensoren und Messsysteme 2010, Nürnberg, Germany
• Q. Hamp, L.M. Reindl
  Graph analysis on uncertain measurements for position estimation
  2010 Proceedings Informatik, GI-Edition, Leipzig, Germany , volume: 2
• R. Nopper, R. Niekrawietz, L.M. Reindl
  Induktiv gekoppelte passive Sensoren für Messungen in schwer zugänglichen Umgebungen
  2010 Sensoren und Messsysteme
• Q. Hamp, M. Eitelberg, B.-S. Lee, T. Becker, D. Wiebeck, L.M. Reindl
  Information Fusion based on graph analysis during Urban Search and Rescue
  2010 Proceedings Information Fusion. IET, Edinburgh, UK
• H. Wegert, E. Mayer, L.M. Reind, W. Ruile, A.P. Mayer
  Interaction of SAWs with Resonating Structures on the Surface
  2010 Proceedings of IEEE International Ultrasonics Symposium, San Diego, USA , pages: 185 - 188
• G. Bruckner, J. Bardong, R. Fachberger, E. Forsen, D. Eisele
  Investigations of SAW delay lines on c-plane AlN/sapphire at elevated temperatures
  2010 Frequency Control Symposium, Newport Beach, CA, USA , pages: 499 - 502
  » show abstract« hide abstract
  Abstract

  Aluminum nitride (AlN) on sapphire is a promising substrate for SAW (surface acoustic wave) sensors operating at high temperatures and high frequencies. To get an experimental measure of the suitability and temperature stability of such devices, several samples of SAW delay lines were fabricated on 2" c-plane (0001) sapphire substrates with 1 μm c-plane AlN layer on top. Time- and frequency responses were recorded during annealing treatments at temperatures up to 850°C and the signals were analyzed afterwards.
• L. Chen, M. Loschonsky, L.M. Reindl
  Large-Scale Fading Model for Mobile Communications in Disaster and Salvage Scenarios
  2010 IEEE International Conference on Wireless Communications and Signal Processing (WCSP 2010), Suzhou, China
• G.U. Gamm, M. Sippel, M. Kostic, L.M. Reindl
  Low power wake-up receiver for wireless sensor nodes
  2010 Proc. IEEE International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP’10), Brisbane, Australia
• L. Chen, T. Ostertag, M. Loschonsky, L.M. Reindl
  Measurement of Mobile Radio Propagation Channel in Ruins
  2010 Beijing, China IEEE Int. conf. on wireless communication, networking and information security (WCNIS)
• F. Höflinger, L.M. Reindl
  Micro-IMU based Multiple Object Control (MOC)-Pointer
  2010 Proc. of Nagoya University - University of Freiburg, International Workshop, Nagoya, Japan
• F. Höflinger, L.M. Reindl
  Micro-IMU based Multiple Object Control (MOC)-Pointer
  2010 Proc. of Micro Alliance Symposium , Kyoto, Japan
• F. Höflinger, L.M. Reindl
  Micro-IMU based Multiple Object Control (MOC)-Pointer
  2010 Proc. of Global COE Workshop 10 - Secure-Life Electronics , Tokyo, Japan
• L. Chen, Ch. Feige, M. Loschonsky, L.M. Reindl
  Modellierung und Vermessung der Mobilfunkkanäle in Katastrophen und Bergungsszenarien
  2010 15. Fachtagung, Nürnberg Sensor und Messsysteme 2010, pages: 367 - 373
• G.U. Gamm, L.M. Reindl
  Passive wake-up scheme for wireless sensor nodes
  2010 Proc. of Nagoya University - University of Freiburg, International Workshop, Nagoya, Japan
• G.U. Gamm, L.M. Reindl
  Passive wake-up scheme for wireless sensor nodes
  2010 Proc. of Micro Alliance Symposium , Kyoto, Japan
• G.U. Gamm, L.M. Reindl
  Passive wake-up scheme for wireless sensor nodes
  2010 Proc. of Global COE Workshop 10 - Secure-Life Electronics , Tokyo, Japan
• Q. Hamp, L.M. Reindl
  Performance of fusion methods for Urban Search and Rescue
  2010 Proceedings IEEE Technologies for Homeland Security, Boston, USA
• C. Feige, T. Ostertag, M. Loschonsky, L.M. Reindl
  Radar assisted detection of passive electronic components
  2010 New Orleans, LA, USA IEEE Radio & Wireless Symposium, pages: 200 - 203
  » show abstract« hide abstract
  Abstract

  In this contribution a radar assisted method is presented for the search for persons buried e.g. in collapsed buildings. Classical detection technology covers borescopes and geophones in combination with K-9 units (search and rescue dogs) for search and rescue missions in ruins, detritus and cones of debris. An improved and time efficient approach for search of vital signs can be realized with UWB (ultra wide band) radar systems, where a very short wide band pulse is transmitted, or with continuous wave (CW) radar systems for measuring movements like respiration. But instead of searching these vital sings, the presented method aims for people carrying electronic RF-devices. The search for these electronic RF-devices can be assisted with pulse radar systems. Frequency filters of such devices can be exposed to a radar pulse near the filters’ resonance frequency and an echo can be detected, which enables the localization of the device and hopefully of the owner, too.
• G.U. Gamm, M. Kostic, L.M. Reindl
  Sensorknoten mit asynchronem Low- Power Aufweckempfaenger
  2010 Proc. of 15. ITG-/GMA Fachtagung Sensoren und Messsysteme (SENS’10), Nuernberg, Germany
• I. Shrena, D. Eisele, J. Bardong, L.M. Reindl
  Signalverarbeitungsalgorithmus zur hochpräzisen Auswertung der Temperaturabhängigkeit von OFW-Eigenschaften
  2010

2009

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• M.T. Penella, J. Albesa, M. Gasulla
  Powering Wireless Sensor Nodes: Primary Batteries versus Energy Harvesting
  2009 Proceedings of I2MTC 2009 , pages: 1625 - 1630
• J. Albesa, M. Gasulla
  Intra-vehicular Wireless Sensor Networks
  2009 FITICA'09- Fórum Internacional de las TIC en la automoción 2009
• J. Müller, A. Rottmann, L.M. Reindl, W. Burgard
  A Probabilistic Sonar Sensor Model for Robust Localization of a Small-size Blimp in Indoor Environments using a Particle Filter
  2009 accepted for IEEE International Conference on Robotics and Automation, Kobe, Japan IEEE International Conference on Robotics and Automation
• D. Haller, J. Hempel, A. Paetzold, N. Losse, I. Peltzer, W. Nitsche, R. King, P. Woias
  A piezo-actuated closed loop MEMS system for active delay of transition
  2009 Solid-State Sensors, Actuators and Microsystems Conference, TRANSDUCERS, Denver, CO, USA, 21-25 June,
• W. Warta, M.C. Schubert, H. Habenicht, M. Kasemann, W. Kwapil, P. Gundel
  Analysis of performance limiting material properties of multicrystalline silicon
  2009 Proceedings of the 18th International Photovoltaic Science and Engineering Conference, Kalkota, India
• E. Mayer, I. Shrena, D. Eisele, J. Bardong, M. Schmitt, L.M. Reindl
  Characterization of Langasite as a Material for SAW Based RFID and Sensing Systems at High Temperatures
  2009 Cavtat, Croatia Proc. IEEE MTT-S International Microwave Workshop on Wireless Sensing, Local Positioning, and RFID
• M. Freunek(Müller), J. Wienold, W.D. Walker, L.M. Reindl
  Characterization of indoor photovoltaic devices and light
  2009 7.–12. Juni 2009, Philadelphia, USA 34th IEEE Photovoltaic Specialist Conference, pages: 738 - 743
• M. Kreitmair, L.M. Reindl, M. Freunek(Müller), M. Freunek, T. Ungan
  Current Status of Technology, Field of Applications, and Outlook
  2009 MRS Fall Meeting, Tutorial Z, Boston MRS Fall Meeting
• H. Hoppe, M. Seeland, F. Kühnlenz, G. Gobsch, M. Kasemann, W. Warta
  Device performance dependency on production impurities and degradation of metallic contacts in polymer solar cells
  2009 European Material Research Society Spring Meeting, Strasbourg, France
• R. Nopper, R. Niekrawietz, L.M. Reindl
  Drahtloses Auswertesystem für kapazitive Sensoren
  2009 accepted for Mikrosystemtechnik Kongress, Berlin Mikrosystemtechnik Kongress
• R. Nopper, R. Niekrawietz, L.M. Reindl
  Drahtloses Auswertesystem für kapazitive Sensoren
  2009 accepted for Mikrosystemtechnik Kongress, Berlin, Germany
• E. Mayer, L.M. Reindl, V. Plessky, A.P. Mayer
  Four-Wave Interaction in 2D Periodic Structures
  2009 Rome, Italy Proceedings of 2009 IEEE Ultrasonics Symposium
• I. Shrena, D. Eisele, J. Bardong, L.M. Reind
  High precision signal processing algorithm to evaluate the SAW properties as a function of temperature
  2009 Proceedings of IEEE Ultrasonics Symposium (IUS), Roma, Italy , pages: 863 - 866
• T. Jäger, P. Sulzberger, K. Wulff, L.M. Reindl
  Integrated Low-Power RFID-S-System for Online Temperature and High-Resolution Displacement Monitoring on High Speed Spindle Rotors
  2009 Croatia Proc. of IEEE MTT-S Int. Microwave Workshop Series on Wireless Sensing, Local Positioning, and RFID, ISBN 978-1-4244-5062
  » show abstract« hide abstract
  Abstract

  This paper presents a low-power RFID-S-system for condition monitoring in high-speed motor spindles. In modern metal cutting machine tools the machining result strongly depends on the motor spindles accuracy. Latest developments on high-speed cutting (hsc) and high-performance cutting (hpc) are leading to substantial increasing temperatures and mechanical elongations of the machine parts, which are resulting in decreasing machining precision. Beside wired sensors on stationary parts, temperature- and displacement-measuring systems on fast rotational dynamic shafts like the spindles rotor are very important, since this is the direct interface between the machine tool and the work piece. Different approaches for laboratory setups are known from literature [1], [2]. In this work, a fully spindleintegrated and tested solution suitable for mass production is presented.
• M. Freunek(Müller), M. Freunek, T. Ungan, L.M. Reindl
  Micro Energy Harvesting: Stand der Technik in Industrie und Wissenschaft
  2009 Berlin Proc. Ambient Assisted Living
• O. Breitenstein, J. Bauer, J.-M. Wagner, H. Blumtritt, A. Lotnyk, M. Kasemann, W. Kwapil, W. Warta
  Physical mechanisms of breakdown in multicrystalline silicon solar cells
  2009 Proceedings of the 34th IEEE Photovoltaic specialists conference, Philadelphia, PA, USA , pages: 000181 - 000186
• W. Kwapil, M. Kasemann, P. Gundel, M.C. Schubert, W. Warta, O. Breitenstein, J. Bauer, A. Lotnyk, J.M. Wagner, P.C.P. Bronsveld
  Physical mechanisms of breakdown in multicrystalline silicon solar cells
  2009 24th European Photovoltaic Solar Energy Conference, Hamburg, Germany
• T. Ungan, X. Le Polozec, W. Walker, L.M. Reindl
  RF energy harvesting design using high Q resonators
  2009 Cavtat, Croatia Proc. of IMWS 2009, IEEE MTT-S International Microwave Workshop on Wireless Sensing, Local Positioning, and RFID, pages: 1 - 4
  » show abstract« hide abstract
  Abstract

  This paper presents a new method for rectifying low ambient radiation sources to supply autonomous measurement systems such as microsystems. An impedance transformation with high quality factor (Q) in front of a Schottky-Diode using a quartz resonator at 24 MHz is presented. In addition to an analytic computation and nonlinear simulation of the rectifier circuit with Advanced Design System (ADS) software, the circuit was built and the efficiency of the RF Energy Harvesting system was measured. The design has been optimized to achieve maximum sensitivity. The measurement results show a sensitivity of -30 dBm (1 µW) for DC output voltage of 1 V and an efficiency of more than 22 %.
• I. Shrena, D. Eisele, E. Mayer, J. Bardong, M. Schmitt, L.M. Reindl
  SAW-Properties of Langasite at High Temperatures: Measurement and Analysis
  2009 Proceedings of International Conference on Signals,Circuits and Systems, Djerba
• J.A. Giesecke, M. Kasemann, W. Warta
  Separation of recombination properties of silicon solar cells and wafers via luminescence imaging
  2009 Proceedings of the 24th European Photovoltaic Solar Energy Conference, Hamburg, germany
• M. Freunek(Müller), H. Hildebrandt, W.D. Walker, L.M. Reindl
  Simulations and measurements for indoor photovoltaic devices
  2009 21.-25. September, Hamburg 24th European Photovoltaic Specialist Conference
• M. Glatthaar, J.A. Giesecke, M. Kasemann, J. Haunschild, M. The, W. Warta, S. Rein
  Spatially resolved determination of the dark saturation current by electroluminescence imaging
  2009 of the 18th International Photovoltaic Science and Engineering Conference
• M. Seeland, F. Kühnlenz, H. Hoppe, G. Gobsch, M. Kasemann, W. Warta
  Spatially resolved luminescence measurements on polymer photovoltaic cells
  2009 Verhandlungen der Deutschen Physikalischen Gesellschaft, Dresden, Germany
• D. Grgić, T. Ungan, M. Kostić, L.M. Reindl
  Ultra-low input voltage DC–DC converter for micro energy harvesting
  2009 Proceedings of PowerMEMS , pages: 265 - 268
  
   
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• M. Kasemann, J.A. Giesecke, W. Kwapil, B. Michl, M. Seeland, H. Hoppe, W. Warta
  What Photons tell us about solar cells – imaging diagnostic techniques
  2009 Optical Society of America meeting on optics and photonics for advanced energy technology, Cambridge, MA, USA
• L.M. Reindl
  Wireless Passive Sensors
  2009 Tutorial, Eurosensors, Dresden Eurosensors
• L.M. Reindl
  Wireless Passive Sensors
  2009 Tutorial, IEEE Sensor, Lecce, Italy IEEE Sensor
• L.M. Reindl
  Wireless Passive Sensors
  2009 Tutorial, IFC, Dresden IFC
• L.M. Reindl
  Wireless Passive Sensors
  2009 Tutorial, USS, Roma USS
• T. Ungan, M. Freunek, M. Freunek(Müller), W.D. Walker, L.M. Reindl
  Wireless energy transmission using electrically small antennas
  2009 San Diego, USA IEEE Radio & Wireless Symposium, pages: 526 - 529
  » show abstract« hide abstract
  Abstract

  This paper presents a concept for rectifying low ambient radiation sources to supply autonomous measurement systems such as microsystems. In addition to an analytic computation and nonlinear simulation of the rectifier circuit with Advanced Design System (ADS), a circuit was built and the efficiency factor of the RF-Harvesting system was measured. Matching the impedance is done by using an electrically small loop-antenna. A resonance circuit transformation with a high quality factor in front of a Schottky-Diode works as a passive voltage transformer with a gain of 30 at 300MHz. The measurements are in excellent agreement with calculations and simulations.

2008

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• M. Loschonsky, A. Dadgar, M. Wieneke, J. Bläsing, A. Krost, S. Ballandras, K. Samm, L.M. Reindl
  Akustische Dünnschichtscherwellenresonatoren für die Wägung kleinster Massen
  2008 Ludwigsburg 14. GMA/ITG-Fachtagung Sensoren und Messsysteme
• D. Grote, M. Hermle, E. Wotke, U. Belledin, M. Hörteis, M. Spitz, M. Kasemann, S. Rein, D. Biro, W. Warta
  Analyzing the Effects of Laterally Varying Emitter Sheet Resistances on Solar Cell Results Using Different Simulation Techniques
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 278
• B. Michl, M. Kasemann, J. Giesecke, M. Glatthaar, A. Schütt, J. Carstensen, H. Föll, S. Rein, W. Warta, H. Nagel
  Application of luminescence imaging based series resistance measurement methods in an industrial environment
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 1176
• J. Hiller, S. Schindler, T. Fuchs, F. Porsch
  Bestimmung des lokalen räumlichen Auflösungsvermögens eines industriellen Mikro-Computertomographie-Systems (µCT) mit Hilfe einer CT-Modulationsübertragungsfunktion
  2008 Ludwigsburg Sensoren und Messsysteme 2008, volume: 2011, pages: 507 - 520
• M. Freunek(Müller), L.M. Reindl, T. Speck, W. Walker
  Biomimetic Energy Concept for Autonomous Micro Systems
  2008 University of Southampton, Chilworth Manor, Southampton, UK Biological Approaches for Engineering, pages: 107 - 111
  » show abstract« hide abstract
  Abstract

  A topic of high interest in the field of micro system technologies is to power autonomous micro systems (AMS) such as sensor nodes using ambient energy. This concept is known as Micro Energy Scavenging. Typically small and varying amounts of ambient energy, as well as the need for a reliable, effective storage are significant challenges (Mackensen, 2006). This work investigates the potential of using a biomimetic approach to the energy supply of AMS. The main idea is not to work on isolated components, but to find biomimetic design principles for complete micro energy harvesting systems. The authors relate energy concepts of Nature to the requirements and settings of AMS. A special focus is made on the most challenging problems of AMS. Examples of current biomimetic research are presented. In contrast to the energy supply of established technical systems, there exist many analogies between AMS and the energy concepts found in Nature. As a result, using a biomimetic energy concept for a complete micro energy scavenging system seems to be a promising approach. Suggestions for a biomimetic system concept are presented.
• J.A. Giesecke, M. Kasemann, M.C. Schubert, B. Michl, M. The, W. Warta, P. Würfel
  Determination of Minority Carrier Diffusion Lengths in Silicon Solar Cells from Photoluminescence Images
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain Proceedings of the 23rd European Photovoltaic Solar Energy Conference, page: 453
• T. Jäger, R. Huber, M. Hobler, D. Ruf, L.M. Reindl
  Einsatz der Mikrosystemtechnik zur Zustands- und Prozessüberwachung im Anlagen und Maschinenbau
  2008 Freiburg Proc. of IMTEK Postersession
• T.M. Wendt, L.M. Reindl
  Energiesparen durch den Einsatz von Aufweckstrategien in drahtlosen Sensor Netzwerken
  2008 Ludwigsburg Sensoren und Messysteme 2008, ISBN 978-3-18-092011-5, volume: 2011
  » show abstract« hide abstract
  Abstract

  In industriellen Anwendungen werden drahtlose Sensornetzwerke immer wichtiger. Auch die Forschung nimmt sich dieser Technologie mehr und mehr an. Die Aufgabenbereiche für drahtlose Sensornetzwerke [1] sind vielfältig. Überall dort, wo es Messwerte von Sensoren zu übertragen gibt, können diese Netzwerke zu finden sein. Die wichtigsten Einsatzgebiete sind Sensornetzwerke in Anwendungen, bei denen man keine Kabel legen kann oder möchte. Verarbeitungsschritte werden vom Hostknoten an die Sensorknoten delegiert, damit der Kommunikationsaufwand minimiert wird. Es werden keine einzelnen Messwerte übertragen. Messwerte die übertragen werden müssen haben vielfach höheren Energieverbrauch im Vergleich zu Messwerten, die direkt im Sensorknoten verarbeitetet werden. Die einzelnen Sensorknoten sind mittlerweile sehr hochtechnologische Baugruppen. Diese können über Sensoren für z.B. Temperatur, Feuchte, Luftdruck oder Erdbeschleunigung verfügen [8]. Die Sensoren haben ebenso wie die Empfänger der Sensorknoten oft einen hohen Eigenenergiebedarf. All diese Faktoren führen dazu, dass die Sensorknoten immer größere Batterien benötigen um eine geforderte Lebenszeit zu erfüllen. Die Aufweckstrategie weckt nur dann einen Sensorknoten auf, wenn neue Messdaten benötigt werden. Aufwecken bedeuten in diesem Zusammenhang, dass der Sensorknoten von einem Energiesparmodus in den Betriebsmodus wechselt. Somit ist die Betriebszeit des Knotens auf ein Minimum reduziert, der Energiebedarf sinkt und die Lebensdauer wird erhöht [10]. Das Design der Sensorknoten wird auf Energiebedarf untersucht und die Art des Betriebs wird optimiert. Die Aufweckstrategien sind der Hauptfokus dieser Arbeit.
• T. Ungan, L.M. Reindl
  Energieversorgung autarker Mikrosysteme durch Nutzung von HF-Strahlungsquellen
  2008 Berlin Ambient Assisted Living Komgress, pages: 433 - 435
  » show abstract« hide abstract
  Abstract

  In dieser Arbeit wird ein Konzept zur Gleichrichtung ambienter Strahlungsquellen für autarke Mikrosysteme vorgestellt (Elektrosmog-Recycling). Neben analytischer Berechnung und nichtlinearer Simulation der Gleichrichterschaltung mit dem Programm ADS (Advanced Design System) wurde die Schaltung gebaut und auf ihren Wirkungsgrad hin gemessen. Als gleichzurichtende HF-Leistung wurde eine 2.6μWatt (-26dBm) starke Quelle, die eine Impedanz von 50Ohm bei 900Mhz hat, angenommen. Durch günstige Anpassung der Impedanz und einer Resonanzkreis-Transformation hoher Güte vor einer Schottky-Diode wurde eine Spannungspumpe (Charge Pump) mit dem Faktor 28 realisiert.
• M. Freunek(Müller), M. Freunek, L.M. Reindl
  Energy Harvesting im Ambient Assisted Living Sector
  2008 Berlin Ambient Assisted Living, 1. Deutscher Kongress, Technologien – Anwendungen – Management, pages: 209 - 214
  » show abstract« hide abstract
  Abstract

  Sensoren bilden die Basis eines intelligenten Gebäudes. Durch die Ermittlung des Umgebungszustandes liefern sie entscheidende Informationen, die komplexe Funktionen wie bedarfsgerechte Energieversorgung, Homemoni-toring oder Selbst lernenden Alarm ermöglichen. Dabei hängt die ermöglichte Funktionalität wesentlich von der Zahl der eingesetzten Sensoren ab. Ein intelligentes Gebäude wird also in bisher unbekanntem Maße Sensoren einsetzen. Das bedeutet in vielen Fällen auch eine nachträgliche Installation einer Vielzahl von Sensoren in eine bestehende Architektur. Die Ansprüche an eine einfache und kostengünstige Installation der Sensoren sind da-durch ebenso hoch wie an die Zuverlässigkeit [1]. Der Betrieb der Sensoren muss im Hinblick auf Wartungskos-ten und Nutzerkomfort zudem optimalerweise wartungsfrei sein. Diese Anforderungen sind insbesondere eine Frage der Energieversorgung Mit den bestehenden Konzepten wie Batterien und Kabeln sind eben diese nicht umsetzbar. In diesem Beitrag wird ein hochinnovatives und äußerst Erfolg versprechendes Konzept zur Lösung der genannten Probleme vorgestellt: "Micro Energy Harvesting'' (MEH), die Gewinnung der notwendigen Ener-gie der Sensorknoten aus der lokalen Umgebung [2]. Beispiel hierfür ist die Nutzung von Licht-, Wärme- oder Vibrations-Energie. Während die Wandlung von Lichtenergie mit Hilfe von Solarzellen bereits gut erforscht und in ersten AAL Systemen eingesetzt wird, sind alternative Generatoren zur Nutzung weiterer Energiequellen not-wendig, aber weitgehend unerforscht [3]. Die Autoren stellen mögliche Energiequellen, Wandler und deren An-wendungspotenzial im AAL-Bereich vor.
• M. Sippel, A. Abdul-Majeed, W. Kuntz, L.M. Reindl
  Enhancing the Accuracy of an Indoor Radar by the Implementation of a Quaternion - and Unscented Kalman Filter - based lightweight, planar, strapdown IMU
  2008 Toulouse, France European Navigation Conference - Global Navigation Satellite Systems (ENC-GNSS)
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  Abstract

  In this paper, we present the hard- and software design, assembly, and implementation of a highly integrated, lightweight, planar, strapdown Inertial Measurement Unit (IMU) with sensors in MEMS technology. Our sensor data fusion algorithm for the orientation output is a quaternion based Unscented Kalman Filter (UKF). We describe the individual sensors we are using as well as their performance, and finally we present the improved accuracy of an indoor radar, equipped with our IMU and our quaternion based Unscented Kalman Filter.
• T.M. Wendt, L.M. Reindl
  Evaluation of wake up methods in battery powered wireless sensor network
  2008 Stockholm, Sweden ICT-MobileSummit 2008
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  Abstract

  The focus of this work is to compare and evaluate wake-up solutions for battery driven wireless sensor applications [1]. A custom demonstration platform has been developed to evaluate these strategies. There is an increasing demand in industrial applications for wireless sensor nodes capable of a long life cycle. These applications typically involve remote operation and may be subjected to harsh environmental conditions where maintenance may be difficult or impossible. The power consumption in wireless sensor networks is a primary consideration in the design of sensor nodes. The life cycle of a sensor node may be limited by the available energy density of batteries for a given battery size, and the difficulty of recharging the battery [8]. Wake-up methods can be used to expand the operational life cycle of sensor nodes by reducing their power consumption. Test results show that wake-up strategies used in conjunction with turning off unneeded components will extend the life-time enormously.
• T. Jäger, K. Wulff, L.M. Reindl
  Fluidic-Coupled High-Resolution Displacement Sensor for Low-Power Wireless Applications
  2008 Lecce, Italy IEEE Conference on Sensors
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  Abstract

  Abstract—This paper presents an innovative high-resolution displacement sensor for low-power-applications, such as wireless systems. The sensor uses the principle of fluidic coupled displacement pressure conversion. The sensor core is based on a piezo-resistive silicon pressure sensor element. A membrane detects the displacement to be measured and changes the pressure of a partly compressible fluid. The change in pressure is then determined by measuring the sensor resistance. In addition, the on-chip temperature is measured and used to increase the sensor accuracy. The measurement range depends on the fluid compressibility and has a typical value of 50 - 100 μm with a resolution of 1 μm. A functional model has been realized and tested in respect to resolution and reliability. Using multiple smart-system integration, a sensor size of 6 mm in diameter and 25 mm in length could be realized.
• M. Sippel, W. Kuntz, L.M. Reindl
  GNSS augmented with Precise Laser Tracking
  2008 Monterey, California, United States, May 5-8 Position Location and Navigation Symposium (PLANS)
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  Abstract

  In this paper, we present the design of a laser tracking system using intelligent sensor nodes. We describe the individual components of the system as well as the related performance we achieve. The system is robust against electromagnetic field interferences and environmental influences. We present the differences between our precise laser tracker and other tracking systems like indoor radar or GPS, and finally the advantage of a hybrid system.
• T. Ungan, L.M. Reindl
  Harvesting Low Ambient RF-Sources for Autonomous Measurement Systems
  2008 Vancouver Island, Canada, May 12-15 Proceedings of the IEEE International Instrumentation and Measurement Technology Conference I²MTC, pages: 145 - 148
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  Abstract

  This paper presents a concept for rectifying low ambient radiation sources to supply autonomous measurement systems like microsystems. Among an analytic computation and nonlinear simulation of the rectifier circuit with ADS (Advanced Design System), the circuit was built and the efficiency factor of the RF-Harvesting system was measured. A radiation source with the power of 1 μWatt (-30dBm) and an impedance of 50 Ohm at 300 MHz was used. By well matching of the impedance and a resonance circuit transformation with a high quality factor in front of a Schottky-Diode a passive charge pump with the factor of 25 was realized.
• J. Bardong, E. Mayer, L.M. Reindl
  High-Temperature Measurements on SAW-Substrate Langasite
  2008 Toulouse, France Proceedings of the European Frequency and Time Forum
• M. Akresh, W. Walker, L.M. Reindl
  Improved Vortex Flow Meter Using Pre-Filter
  2008 Hammamet, Tunisia SCS' 08-IEEE International Conference on Signals, Circuit & Systems, page: 89
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  Abstract

  Commercial vortex flow meters were first introduced to industrial flow measurement in the early 1970s. Since that time, they have been popular in flow measurement due to their low price and high accuracy. They are used in the measurement of liquid and gas flows. As a liquid or gas passes a bluff body in a pipe, the flow separates and produces vortices. The frequency of the vortex formation in a flow meter can be measured using a piezoelectric sensor. The piezoelectric sensor produces a raw signal, where the average frequency indicates volumetric flow rate. This sensor signal contains more information than just the frequency of vortex. The objective of this research is to optimize a typical flow meter with a measurement range of 0.5–4.5 l/min and also output a signal outside of this measuring range. A vortexsignal is taken directly from a piezoelectric sensor with a flow rate of greater than 4.5 l/min to investigate the sensors capability in sensing a vortex signal in a turbulence range, and to identify the various noises which distort the vortex signal. Based on experimental measurements, an analog pre-filter circuit system has been designed for a typical vortex to solve signalinterference problem, and to extend the measuring range. The pre-filter circuit has been presented for vortex flow meter and can be extended to measure flows up to 7 l/min.
• A. Kiefer, L. M. Reindl
  Inductively Coupled Sensor/Actuator System for Digital Closed-Loop Control Applications at High Operating Temperatures
  2008 Acapulco, Mexico, January 25-27 Proceedings of the 2nd WSEAS International Conference on CIRCUITS, SYSTEMS, SIGNAL and TELECOMMUNICATIONS (CISST'08), pages: 132 - 136
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  Abstract

  This paper presents a sensor/actuator system for high-temperature applications with the complete measurement electronics and sensors integrated into the actuator. The data transmission is implemented as point-to-point Power Line Communication (PLC), between the sensor/actuator system and its control unit. A separable transformer serves as an inductively coupled contactless connector for both power and bidirectional PLC-data, allowing for a perfect hermetic seal. We discuss the increased requirements for the measurement electronics at high operating temperatures and we present a special ratiometric self-calibration technique to eliminate temperature drifts that is also suitable for integration into an Application Specific Integrated Circuit (ASIC).
• M. Loschonsky, D. Eisele, A. Dadgar, A. Krost, S. Ballandras, L.M. Reindl
  Investigations of a-plane and c-plane GaN-Based Synchronous Surface Acoustic Wave Resonators
  2008 Hawaii, USA IEEE International Frequency Control Symposium
• W. Kwapil, M. Kasemann, J. Giesecke, B. Michl, W. Warta
  Investigations on the Pre-Breakdown of Multicrystalline Silicon Solar Cells
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 179
• T. Ungan, L.M. Reindl
  Konzept zur Energieversorgung autarker Mikrosysteme durch Nutzung von HF-Strahlungsquellen
  2008 Ludwigsburg Sensor und Messsysteme 2008, 14. Fachtagung, pages: 899 - 904
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  Abstract

  In dieser Arbeit wird ein Konzept zur Gleichrichtung ambienter Strahlungsquellen für autarke Mikrosysteme vorgestellt. Neben analytischer Berechnung und nichtlinearer Simulation der Gleichrichterschaltung mit dem Programm ADS (Advanced Design System) wurde die Schaltung aufgebaut und auf ihren Wirkungsgrad hin gemessen. Für die Simulation der Schaltung wurde als gleichzurichtende HF-Leistung 2,6 μWatt (-26dBm) angenommen, die eine Impedanz von 50 Ω bei 290 MHz hat. Durch günstige Anpassung der Impedanz und einer Resonanzkreis-Transformation hoher Güte vor einer Schottky-Diode wurde eine Spannungspumpe (Charge Pump) mit dem Faktor 28 realisiert. In der aufgebauten Schaltung konnte in einem Abstand von 2 m zur Basisstation (25dBm) eine gleichgerichtete Leerlaufspannung von 0,3 V gemessen werden.
• M. Freunek, L.M. Reindl, W.D. Walker
  Modified model for thermoelectric generators
  2008 July 2-4, Paris, France ECT Proceedings
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  Abstract

  In this paper we describe a modified analytical model for thermoelectric generators (TEG). The model includes the Peltier heat, a parameterization of the Joule heat, as well as all thermal and electrical resistances. Geometry optimization and investigations of the influence of Peltier heat and the heat sink conditions, which affect the power output, is presented. The results are compared with measurements of commercially available thermoelectric generators and the fundamental thermodynamic limit. A comparison between the generators is performed.
• D. Sun, A. Kleiner, T.M. Wendt
  Multi-Robot Range-Only SLAM by Active Sensor Nodes for Urban Search and Rescue
  2008 Suzhou, China RoboCup Symposium 2008
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  Abstract

  To jointly map an unknown environment with a team of autonomous robots is a challenging problem, particularly in large environments, as for example the devastated area after a disaster. Under such conditions standard methods for Simultaneous Localization And Mapping (SLAM) are difficult to apply due to possible misinterpretations of sensor data, leading to erroneous data association for loop closure. We consider the problem of multi-robot range-only SLAM for robot teams by solving the data association problem with wireless sensor nodes that we designed for this purpose. The memory of these nodes is utilized for the exchange of map data between multiple robots, facilitating loop-closures on jointly generated maps. We introduce RSLAM, which is a variant of FastSlam, extended for range-only measurements and the multi-robot case. Maps are generated from robot odometry and range estimates, which are computed from the RSSI (Received Signal Strength Indication). The proposed method has been extensively tested in USARSim, which serves as basis for the Virtual Robots competition at RoboCup, and by real-world experiments with a team of mobile robots. The presented results indicates that the approach is capable of building consistent maps in presence of real sensor noise, as well as to improve mapping results of multiple robots by data sharing.
• T.M. Wendt, L.M. Reindl
  Multiple Access Methods utilized to extend Operational Life Time of Wireless Sensor Nodes
  2008 Montreal, Canada SysCon 2008 – IEEE International Systems Conference
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  Abstract

  The power consumption in wireless sensor networks is one of the main issues when designing sensor nodes. Furthermore the available energy density of batteries for a given battery size and the difficulty of recharging possibilities limits the life cycle of sensor nodes. Multiple access methods will help to expand the operational life cycle of sensor nodes by reducing their power consumption. The focus of this work is to evaluate multiples access methods wake-up solutions for wireless sensor applications. A custom demonstration platform to perform theses evaluations and measurements has been developed. The current measurements have shown that multiple access [2] wake-up methods in conjunction with switching of not needed components will extend the life cycle of sensor nodes immense
• M. Sippel, A. Rottmann, T. Zitterlell, B. Steder, C. Scholl, W. Burgard, L.M. Reindl
  Multisensor-Navigation für autonome Flugrobote
  2008 Ludwigsburg Sensoren und Messsysteme 2008, pages: 667 - 676
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  Abstract

  In der folgenden Arbeit wird die Konzeption und Implementierung eines Multisensor- Navigationssystems für autonome Flugroboter vorgestellt. Die besonderen Anforderungen an autonome Flugroboter, wie beispielsweise ein minimales Gewicht, geringe Abmessungen der Systemkomponenten und eine geringe Leistungsaufnahme, bedingen eigene Konzepte für fliegende autonome Systeme. Des Weiteren werden für eine autonome Navigation Algorithmen benötigt, die Entscheidungen in Echtzeit treffen und robust mit verrauschten Sensorsignalen umgehen können. In dieser Arbeit stellen wir die einzelnen Systemkomponenten unseres Prallluftschiffs sowie die verwendeten Sensoren vor, die für eine effiziente Positionsbestimmung benötigt werden. Dabei wurde besonderen Wert auf ein System gelegt, das leicht bezüglich weiterer Systemkomponenten erweitert werden kann.
• M. Sippel, W. Kuntz, L.M. Reindl
  New Approach in Precise Laser Tracking
  2008 Victoria, Vancouver Island, Canada, May 12-15 IEEE International Instrumentation and Measurement Technology Conference (IMTC), pages: 446 - 451
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  Abstract

  In this paper, we present the design of a laser tracking system with intelligent sensor nodes. We describe the individual components of the system as well as the related performance we achieve. The system is robust against electromagnetic field interferences and environmental influences. We present the differences between our precise laser tracker and other tracking systems like an indoor radar or GPS and finally the advantage of a hybrid system.
• D. Eisele, T. Jäger, I. Shrena, E. Mayer, L.M. Reindl
  OFW Funktechnologie für Hochtemperatur-Anwendungen
  2008 Düsseldorf EAS 2008, 5. GMM Workshop Energieautarke Sensorik
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  Abstract

  The passive, wireless surface acoustic wave (SAW) technology is suitable for energy self-sufficient sensor systems in harsh industrial environments, beyound the operation range of active semiconductor sensor systems. After a short introduction of the basic principles the possibilities and limits of wireless SAW sensor systems are discussed using the example of high temperature SAW sensor systems. Furthermore, the state of the art research and results on langasite are presented, which is a promising piezoelectric material for high temperature SAW devices. The results includes acoustical properties up to 750°C extracted from measurements.
• J. Bardong, M. Schulz, M. Schmitt, I. Shrena, D. Eisele, E. Mayer, L.M. Reindl, H. Fritze
  Precise measurements of BAW and SAW properties of langasite in the temperature range from 25°C to 1000°C
  2008 Hawaii Proc. IEEE Frequency Control Symposium, pages: 321 - 331
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  Abstract

  There is a high demand for wireless sensing devices in harsh environments for industrial applications. For temperatures above 250°C, silicon-based sensors cannot be used. In contrast, bulk acoustic wave (BAW) and surface acoustic wave (SAW) devices are still suitable for this purpose. Further hightemperature applications include thermogravimetry on small volumes and gas sensing based on stoichiometry change of thin sensor films. Langasite (La3Ga5SiO14) is a piezoelectric single crystal that preserves its piezoelectric properties and is chemically stable up to its melting point at 1470°C without any phase transition and, therefore, is a promising material for hightemperature devices. Using a resonance-antiresonance method based on bulk oscillations, all components of elastic and piezoelectric tensors of langasite have been determined at temperatures up to 900°C. Resonance spectra of several langasite samples have been measured and fitted with the impedance calculated from a one-dimensional physical model of piezoelectric bodies vibrating in several modes. In order to extract the electromechanical parameters, different resonator geometries and orientations are used. Also, the results of measurements are presented for SAW devices on langasite at temperatures from 25 to 750°C. Two cuts with Euler angles (0°, 138.5° , 26.6°) and (0°, 30.1°, 26.6°) have been studied. The devices were fabricated with a platinum (Pt) layer with different heights on a zirconium (Zr) adhesion layer. The main material parameters relevant for SAW devices such as phase velocity vp, propagation loss α and coupling koefficient k² have been obtained. The measured SAW phase velocities compare well with those calculated with the elastic and piezoelectric tensors obtained by bulk-oscillation measurements.
• M. Kasemann, W. Kwapil, B. Walter, J. Giesecke, B. Michl, M. The, J.-M. Wagner, J. Bauer, A. Schütt, J. Carstensen, S. Kluska, F. Granek, H. Kampwerth, P. Gundel, M.C. Schubert, R.A. Bardos, H. Föll, H. Nagel, P. Würfel, T. Trupke, O. Breitenstein, M. Hermle, W. Warta, S.W. Glunz
  Progress in Silicon Solar Cell Characterization with Infrared Imaging Methods
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 965
• D. Ruf, T. Jäger
  Prozessüberwachung durch spindelintegrierte Schwingungsanalyse für Zerspanungsmaschinen
  2008 Winterthur (CH) Tagungsband Internationales Forum Mechatronik (ifm)
• I. Shrena, D. Eisele, E. Mayer, L.M. Reindl, J. Bardong, M. Schmitt
  SAW-Relevant Material Properties of Langasite in the Temperature Range from 25 to 750 °C: New Experimental Results
  2008 Peking Proceedings of IEEE Ultrasonics Symposium, pages: 209 - 212
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  Abstract

  The aim of this work is to determine the acoustical parameters of langasite up to the highest possible point of temperature. This paper presents measurements of transfer functions for delay lines on langasite at frequencies ranging from 150 MHz to 1 GHz, at temperatures from 25 to 750°C. Two cuts with Euler angles (0°, 138.5°, 26.6°) and (0°, 30.2°, 26.6°) have been studied. The devices were fabricated using langasite as substrate, with two different platinum (Pt) layer heights (45 nm and 75 nm), on a zirconium (Zr) adhesion layer (4 nm). A special signal processing algorithm utilizing cross-correlation was implemented in MATLAB and used for the analysis of measured data. The material parameters relevant for SAW devices, such as phase velocity, propagation loss, and electromechanical coupling coefficient, have been determined as a function of temperature.
• M. The, J. Giesecke, M. Kasemann, W. Warta
  Spatially resolved characterisation of silicon as-cut wafers with photoluminescence imaging
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 441
• M. Kasemann, W. Kwapil, M.C. Schubert, H. Habenicht, B. Walter, M. The, S. Kontermann, S. Rein, O. Breitenstein, J. Bauer, A. Lotnyk, B. Michl, H. Nagel, A. Schütt, J. Carstensen, H. Föll, T. Trupke, Y. Augarten, H. Kampwerth, R.A. Bardos, S. Pingel, J. Berghold, W. Warta, S.W. Glunz
  Spatially resolved silicon solar cell characterization using infrared imaging methods
  2008 Proceedings of the 33rd IEEE Photovoltaic specialists conference, San Diego, CA, USA , pages: 1 - 7
• W.D. Walker
  Sub-microdegree Phase Measurement Technique using Lock-in Amplifiers
  2008 Honolulu, Hawaii, USA IEEE Frequency Control Symposium
• B. Walter, M. Kasemann, J. Ebser, W. Kwapil, W. Warta
  Verification of power loss mechanisms contributing to the Illuminated Lock–In Thermography (ILIT) signal
  2008 Proceedings of the 23rd European Photovoltaic Solar Energy Conference, Valencia, Spain , page: 310
• T.M. Wendt, L.M. Reindl
  Wake-Up Methods to Extend Battery Life Time of Wireless Sensor Nodes
  2008 Victoria, Vancouver Island, Canada I²MTC 2008 – IEEE International Instrumentation and Measurement Technology Conference
  » show abstract« hide abstract
  Abstract

  The power consumption in wireless sensor networks is one of the main issues when designing sensor nodes. Furthermore the available energy density of batteries for a given battery size and the difficulty of recharging possibilities limits the life cycle of sensor nodes [8]. Wake up strategies will help to expand the operational life cycle of sensor nodes by reducing their power consumption. The focus of this work is to compare and evaluate wake up solutions for wireless sensor applications [1]. A custom demonstration platform to perform theses evaluations and measurements has been developed. The current measurements at the demonstrator have shown that wake up strategies [11] in conjunction with switching of not needed components will extend the life cycle enormous. In continuous receiving and transmit mode a sensor node will operate for 2-3 hours. If the sensor node is operated in wake up and smart switching mode it can operate up to several years.
• L.M. Reindl
  Wireless Passive Sensors: Basic Principles and Performances
  2008 Lecce, Italy IEEE Conference on Sensors
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  Abstract

  The present work reviews the operating principle of passive resonant high Q wireless sensor systems, like SAW or BAW sensor systems and their state-of-the-art performance by way of a few examples which include the wireless measurement of temperature, pressure, torque, acceleration, magnetic field, and water content of soil.
• M. Loschonsky, D. Eisele, A. Wörz, K. Samm, M. Wieneke, J. Bläsing, A. Dadgar, A. Krost, S. Ballandras, L.M. Reindl
  Wireless Sensor Concepts
  2008 Amman, Jordan Keynote Lecture at the Fifth International IEEE Conference on Systems, Signals and Devices

2007

 back to the year overview

• M. Freunek, M. Freunek(Müller), L.M. Reindl
  Energy Harvesting in the "Ambient Assisted Living" Sector: Thermogenerators for Wireless Patient Monitoring
  2007 Workshop Energy Harvesting - Energieautarke Sensorik. Essen: Haus der Technik
• M. Loschonsky, L.M. Reindl, A. Dadgar, M. Wieneke, J. Bläsing, A. Krost
  A-plane GaN Shear Wave Thin Film Resonator
  2007 IEEE International Frequency Control Symposium 2007 joint with the 21st European Frequency and Time Forum, pages: 494 - 498
• M.C. Schubert, P. Gundel, M. The, M. Kasemann, S. Pingel, W. Warta
  Advances in infrared imaging methods for silicon material characterization
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 32 - 37
• J. Hiller, S. Kasperl
  Analyse von Einflussgrößen beim dimensionellen Messen mittels Röntgencomputertomographie
  2007 Fürth DGZFP Jahrestagung, DGZfP Berichtsband BB 104
• D. Grote, M. Kasemann, M. Hermle, W. Warta
  Analysing lateral inhomogeneities of silicon solar cells using a quasi 3D circuit simulation tool based on SPICE
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 305 - 309
• U. Bartsch, C. Bretthauer, T. Hehn, B. Mack, T. Ungan, Y. Manoli, O. Paul, L.M. Reindl, H. Reinecke, U. Wallrabe, P. Woias
  Angewandtes „Micro Energy Harvesting“-Systemkonzept für energieautarke Mikrosysteme
  2007 Dresden MikroSystemTechnik Kongress 2007, pages: 797 - 800
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  Abstract

  In diesem Beitrag wird ein Teil der Aktivitäten des neuen DFG- und industriegeförderten Graduiertenkollegs GR 1322 mit dem Titel „Micro Energy Harvesting― vorgestellt [1]. Dabei steht ein Systemkonzept im Mittel-punkt, das die Teilgebiete Energiewandlung, elektronische Anpassung und Energiespeicherung umfasst. Die hier auszugsweise vorgestellten Arbeiten zu Energiewandlern beruhen auf dem elektromagnetischen und dem kapazi-tiven Prinzip sowie auf der elektromagnetischen Fernspeisung. Eine elektronische Schaltung transportiert die verfügbare Leistung in einen Zwischenspeicher, der als integrierter Brennstoffzellenakkumulator ausgeführt ist.
• W. Kwapil, M. Kasemann, J. Ebser, S. Rein, W. Warta
  Application of illuminated lock-in thermography to industrial silicon solar cells
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 1596 - 1599
• H. Qasem, L.M. Reindl
  Autonomous precise indoor wireless positioning system based on Range Measurements
  2007 Paris, France Smart System Integration , 1st European Conference and Exhibition on Integration Issues of Miniaturized Systems- MEMS, MOEMS, ICs and Electronic Components
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  Abstract

  We investigate the performance of a real time wireless localization system by implementing two filtering techniques to minimize the tracking errors. An extended kalman filter and particle filter are used to get a better performance of the system. The presented measurement system consists of a mobile radar base station, implemented as a real-time embedded system, and four active transponders.The system measures the range between the transponders and the base station like Frequency Modulated Continuous Wave (FMCW) radar by comparing the instantaneous frequencies of the transmitted and received signals. Process and measurement error models are derived and analysed. Results obtained shows that particle filter outer performs extended kalman filter in nonlinear situations. Error distribution density functions based on the measured data and the characteristics of the test environment are statistically developed, analysed and illustrated.
• H. Qasem, L.M. Reindl
  Comparison between particle filter and extended kalman filter for localizing a mobile vehicle in indoor harsh environment
  2007 Nürnberg Sensor Conference 2007
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  Abstract

  This work presents a comparison between two localization algorithms, an Extended Kalman Filter (EKF) and Particle Filter (PF), using real time range measurements obtained from radar based-system. With four transponders and one mobile base station, the system provides real time the radians to transponders three times per second like a frequency modulated continuous wave radar signal in 5.8 GHz ISM band. EKF, PF are employed in order to get a better accuracy. Detailed structures of both algorithms are presented. Results including localization accuracy and error model for each filter are demonstrated.
• T. Ungan, L.M. Reindl
  Concept for Harvesting Low Ambient RF-Sources for Microsystems
  2007 Freiburg PowerMEMS 2007, 7th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applicatons, pages: 293 - 295
  » show abstract« hide abstract
  Abstract

  This paper presents a Concept for rectifying low ambient radiation sources to supply Microsystems. A radiation source with the power of 2.5 μWatt (-26dBm) and an Impedance of 50 Ohm by 900 MHz was used. By well matching of the impedance and a resonance circuit transformation with a high quality factor in front of a Schottky-Diode a charge pump with the factor of 28 was realized.
• H. Qasem Mahamda, O. Gorgis, L.M. Reindl
  Design and Calibration of an Inertial Navigation Sensor Node for Precise Tracking
  2007 Cairo, Egypt 12th WSEAS International Conference on APPLIED MATHEMATICS
• H. Qasem, O. Gorgis, M. Kostic, L.M. Reindl
  Development of an Inertial Navigation System for Determining the Pose of a Mobile Vehicle
  2007 15.-17. Oktober, Dresden, Germany Micro-System Technology Congress
• T. Jewula, W. Ruile, H. Zidek, D. Courty, L.M. Reindl
  Einfluss von Verlustmechanismen in OFW-Bauteilen auf die Akustomigration
  2007 Dresden Mikrosystemtechnik-Kongress 2007
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  Abstract

  Die stress- und temperaturabhängigen Veränderungsprozesse in den Metallstrukturen der Oberflächenwellenbauteile beeinflussen ihre Filtereigenschaften und führen im Extremfall zum Totalausfall. Dieses als Akustomigration bekanntes Phänomen ist ein zweistufiger Vorgang: zunächst werden die Spannungsfelder an den Korngrenzen infolge der plastischen Verformung des Materials erzeugt, welche danach durch temperaturabhängige Materialdiffusionsprozesse wieder abgebaut werden. Es wurde experimentell gezeigt, dass diese Schädigung sehr stark von dem auf die Übertragungsfunktion des Filters bezogenen Belastungspunkt abhängt. Um die Ursache dieses Verhaltens zu erklären, wurden die Verluste und die damit verbundene Eigenerwärmung in den OFW-Teststrukturen berechnet. Die Untersuchungen zeigen, dass sich in den Frequenzbereichen der größten Verluste und damit der höchsten Eigenerwärmung auch die maximalen Stressbelastungen der Elektroden ergeben. Diese Stellen sind damit die empfindlichsten Belastungspunkte der OFW-Bauteile, was durch Lebensdauermessungen bestätigt werden konnte.
• H. Qasem, L.M. Reindl
  Enhanced Local Positioning Radar with Predictive Filters
  2007 accepted as presentation in the the 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communicatios (PIMR’07), 3.-7. September, IEEE, Athens, Greece PIMR’07
• T. Jäger, M. Hobler, D. Ruf, F. Timmler
  Funksensoren mit induktiver Energieversorgung im Maschinenbau
  2007 Ulm Proc. of EEEfCom - Workshop Hochfrequenzelektronik
• M. Kostic, M. Loschonsky, L.M. Reindl
  In-situ characterisation of droplets condensed on a surface
  2007 accepted for presentation at SENSOR Conference 2007, Nürnberg, Germany, 22-24 May SENSOR Conference 2007
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  Abstract

  A new method for characterising water droplets condensed on a surface is presented. In order to obtain the size distribution of the droplets a two mega pixel CMOS image sensor is placed on the surface of interest. The micro lens of each pixel of the sensor focuses all incident light beams within a certain angle range. Due to the light refraction, a water droplet condensing directly on the active pixel array of the image sensor can be clearly detected as a circle with a dark border on the image delivered by the sensor. The high resolution of the image sensor provides detection of droplets with a minimum diameter of a few pixels, where the area of one pixel is 2.8 μm x 2.8 μm. The volume of a droplet is determined by its diameter and the contact angle of the droplet with the sensor surface. Our image data show a correlation between this contact angle and the ratio of the dark border to the droplet diameter, with a regression factor better than R² = 0.99.
• M. Kostic, M. Loschonsky, L.M. Reindl
  In-situ characterisation of droplets condensed on a surface
  2007 Hammamet-Tunisia Fourth International IEEE Conference on Systems, Signals & Devices
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  Abstract

  A new method for characterising water droplets condensed on a surface is presented. In order to obtain the size distribution of the droplets a two mega pixel CMOS image sensor is placed on the surface of interest. The micro lens of each pixel of the sensor focuses all incident light beams within a certain angle range. Due to the light refraction, a water droplet condensing directly on the active pixel array of the image sensor can be clearly detected as a circle with a dark border on the image delivered by the sensor. The high resolution of the image sensor provides detection of droplets with a minimum diameter of a few pixels, where the area of one pixel is 2.8 μm x 2.8 μm. The volume of a droplet is determined by its diameter and the contact angle of the droplet with the sensor surface. Our image data show a correlation between this contact angle and the ratio of the dark border to the droplet diameter, with a regression factor better than R² = 0.99
• A. Kiefer, L. M. Reindl
  Inductively Coupled Sensor/Actuator System for Closed-Loop Control Applications at High Temperatures and in Aggressive Environments
  2007 Atlanta, USA Electronic Proceedings of the Sixth IEEE SENSORS Conference, pages: 1396 - 1399
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  Abstract

  This paper presents a sensor/actuator system for high-temperature applications with the complete measurement electronics and sensors integrated into the actuator. The data transmission is implemented as point-to-point Power Line Communication (PLC), between the sensor/actuator system and its control unit. A separable transformer serves as an inductively coupled contactless connector for both power and bidirectional PLC-data, allowing for a perfect hermetic seal. We discuss the increased requirements for the measurement electronics at high operating temperatures and we present a special ratiometric self-calibration technique to eliminate temperature drifts that is also suitable for integration into an Application Specific Integrated Circuit (ASIC).
• T. Jäger, R. Huber, M. Hobler, D. Ruf, F. Timmler
  Intelligenz im Metall – Einsatz der Mikrosystemtechnik zur Zustands und Prozessüberwachung im Anlagen- und Maschinenbau
  2007 Dresden Proc. of Mikrosystemtechnik-Kongress, ISBN 978-3-8007-3061-2, VDE-Verlag, pages: 1073 - 1078
• Grohe, A., Nekarda, J., Hofmann, M., Catoir, J., Fleischhauer, B., Schneiderlöchner, E., Glunz, S., Preu, R
  Laser Technology for Contacting High-Efficiency Silicon Solar Cells - the Laser-Fired Contacts Approach
  2007 Workshop: Laser Technology in Photovoltaics, photonicnet.de, Hameln, Germany
• A. Kiefer, L. M. Reindl
  Low Cost Sensors for High Temperature Actuators using Power Line Communication
  2007 AMA, Nürnberg, Germany SENSOR Proceedings, volume: 1, pages: 313 - 318
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  Abstract

  High power actuators used in process engineering are often working at high operating temperatures. Usually the required instrumentation is arranged in a way that only the sensor element itself is exposed to the high temperatures and the corresponding measurement electronics is located further away. But this practice requires complex and expensive cabling effort. In this paper we present a measuring system for high temperature applications with the complete measurement electronics and sensors integrated into the power actuator. The data transmission is implemented as point-to-point Power Line Communication to the corresponding control unit. Through this, no additional cabling for instrumentation purposes is necessary. We discuss the increased requirements for the electronics at higher operating temperatures by concurrently following a low cost solution. The implemented measuring system and its components are described and cost savings are pointed out.
• A. Kiefer, L. M. Reindl
  Low Cost Sensors for High Temperature Actuators using Power Line Communication
  2007 Freiburg, Germany Proceedings booklet of the IMTEK Poster Session 2007, page: 41
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  Abstract

  Power actuators are often operating at high temperatures and in aggressive environments. Additional sensors for monitoring and control usually require complex cabling and connectors that are prone to errors. In this poster, we present a measuring system for high-temperature applications with the complete measurement electronics and sensors integrated into the power actuator. The data transmission is implemented as point-to-point Power Line Communication (PLC), using the existing power cable between the actuator and its control unit. A separable transformer serves as an inductively coupled contactless connector for both power and bidirectional data.
• M. Sippel, L.M. Reindl
  Messwerterfassung und Sensordatenfusion auf autonomen Flugkörpern
  2007 Paderborn XXI. Messtechnisches Symposium des AHMT, pages: 34 - 39
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  Abstract

  Der nachfolgende Beitrag soll einen kurzen Überblick über die Besonderheiten der Messwerterfassung und der Sensordatenfusion in eingebetteten Mikrosystemen, auf autonomen Flugkörpern liefern. Die besonderen Anforderungen an ein solches System, insbesondere an die Hardware, werden ebenfalls kurz verdeutlicht.
• Fleischhauer, B., Kloke, A., Rubenwolf S., Schuh, K., Schlipf, C., Krüger, M., Müller, C., Prucker, O., Reinecke, H., Rühe, J., Stetten, F. von, Zengerle, R., Woias, P.
  Micro Energy Harvesting durch Mikro-Brennstoffzellen
  2007 Proc. Mikrosystemtechnik-Kongress, Dresden, Germany, VDE Verlag, pages: 349 - 352
• H. Qasem, L.M. Reindl
  Performance evaluation of particle filter and extended kalman filter for precise tracking in indoor industrial environment
  2007 Hammamet-Tunisia Fourth International Conference on Systems, Signals & Devices
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  Abstract

  This work presents a comparison between two localization algorithms, an extended kalman filter and particle filter, using range data obtained from radar based system. With four transponders and one mobile base station, the system provides real time the radians to transponders three times per second like a frequency modulated continuous wave radar operating in 5.8 GHz ISM band. Extended kalman filters, Particle Filter are employed in order to get a better accuracy. Detailed structures of both algorithms are presented. Results including localization accuracy and error model for each filter are demonstrated.
• F. Clement, M. Lutsch, T. Kubera, M. Kasemann, W. Kwapil, C. Harmel, N. Mingirulli, D. Erath, H. Wirth, D. Biro, R. Preu
  Processing and comprehensive characterisation of screen-printed mc-Si metal wrap through (MWT) solar cells
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 1399 - 1402
• T. Trupke, R.A. Bardos, M.D. Abbott, E. Pink, Y. Augarten, F.W. Chen, K. Fisher, J.E. Cotter, M. Kasemann, M. Rüdiger, S. Kontermann, M.C. Schubert, M. The, S.W. Glunz, W. Warta, P. Würfel, D. Macdonald, J. Tan, A. Cuevas, J. Bauer, R. Gupta, O. Breitenstein, T. Buonassisi, G. Tarnowski, A. Lorenz, H.P. Hartmann, D.H. Neuhaus, J.M. Fernandez
  Progress with luminescence imaging for the characterisation of silicon wafers and silicon solar cells
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 22 - 31
• J. Albesa, R. Casas, M.T. Penella, M. Gasulla
  REALnet: An environmental WSN Testbed
  2007 Proceedings of International Conference on Sensor Technologies and Applications-SensorComm 2007 , pages: 502 - 507
• T.M. Wendt, L.M. Reindl
  Reduction of power consumption in wireless sensor networks through utilization of wake up strategies.
  2007 Crete Island, Greece 11th WSEAS CSCC Multiconference, Part 1
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  Abstract

  Long-time operating wireless sensor networks in remote or harsh environmental conditions where maintenance is not simple or impossible to accomplish becoming more and more demand in industrial applications. Wake up strategies will help to expand the operational life cycle of sensor nodes where long life cycles are required. The lack of energy and no recharge possibilities are challenges of wireless sensors nodes. Wake up strategies can address these challenges by reducing the power consumption of senor nodes. The focus of this work is to compare wake up solutions for wireless sensors applications. The space diversity wake up strategy is described in details.
• M. Kasemann, D. Grote, B. Walter, T. Trupke, Y. Augarten, R.A. Bardos, E. Pink, M.D. Abbott, W. Warta
  Shunt detection capabilities of luminescence imaging on silicon solar cells
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy
• M. Kasemann, D. Grote, B. Walter, T. Trupke, Y. Augarten, R.A. Bardos, E. Pink, M.D. Abbott, W. Warta
  Shunt detection capabilities of luminescence imaging on silicon solar cells
  2007 Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milan, Italy , pages: 394 - 399
• H. Qasem, L.M. Reindl
  Sigma-Point Kalman Filter for Precise Indoor Navigation with Real Time Radar Range Measurements
  2007 Hamburg, Germany Workshop and Exhibition on Radar, Communication and Measurement
• A. Rottmann, M. Sippel, T. Zitterell, W. Burgard, L.M. Reindl, C. Scholl
  Towards an Experimental Autonomous Blimp Platform
  2007 Freiburg European Conference on Mobile Robots (ECMR), pages: 19 - 24
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  Abstract

  In this paper, we present the design of an autonomous indoor blimp. We describe the individual low-weight components of an embedded system including actors and sensors which achieve a total weight of less than 170 grams. Both, the modular hardware components and the use of generic hardware interfaces facilitate the adaption to different actor and sensor systems. Similar to the flexibility of the hardware components, the user benefits from a generic software framework. Here, an onboard Linux operating system and device driver interface ease the implementation of robotic applications and control tasks. The main challenge of designing a small blimp in regard to autonomous operation is the efficient interplay of the individual software and hardware components. In this work, we show approaches how to build up such a system which can easily be applied for other robotic systems. In practical applications, we evaluate the performance of the components in conjuction and demonstrate the integration of all components in a reinforcement learning setting.
• H. Qasem, L.M. Reindl
  Unscented and extended kalman estimators for non linear indoor tracking using distance measurements
  2007 Hannover Proceedings of the 4th Workshop on Positioning , Navigation and Communication
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  Abstract

  Industrial und logistic indoor tracking with accuracy in centimetre range is still a challenging issue. Many applications in mining, logistic, and navigation depend mainly on a precise determination of a mobile terminal. This work presents an indoor positioning approach using two recursive tracking algorithms for precisely localizing a mobile vehicle in a noisy environment. An Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF), the corresponding algorithms and mathematical models are presented and analysed. Experimental range measurements obtained from local positioning radar system are used to feed the filters. True and estimated trajectories of the mobile vehicle with associated means and error covariances are presented in more details. Results obtained shows that UKF is slightly more accurate and reliable. Whereas, EKF is easier to implement, converges faster when fed with a good initial estimate and more optimized for semi-linear tracking models.

2006

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• J. H. Kuypers, M. Esashi, D.A. Eisele, L.M. Reindl
  2.45 GHz passive wireless temperature monitoring system featuring parallel sensor interrogation and resolution evaluation
  2006 Proc. 2006 IEEE Sensor Conf.
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  Abstract

  We report on the development of a TDMA based wireless sensor system for temperature monitoring. The transponders consisting of passive surface acoustic wave delay line sensors were designed for operation in the ISM band at 2.45 GHz and for a temperature range from -20 °C to 180 °C. A multi-step evaluation scheme is introduced using a combination of delay and phase analysis. The presented design of these sensors is based on relating the sensor’s effective SNR to the resulting accuracy concerning a delay or phase evaluation. These proposed design rules present a basis for the design of wireless delay line sensors in general, the optimum choice of a pure phase or a combined time delay and phase evaluation scheme, and due to the estimation of phase ambiguity regions, an exact design of multi-step evaluation schemes and their transition. At the same time the SNR relation is of practical value for wireless monitoring systems employed in environments suffering short-term elevated noise levels or temporary obstructions, as the sensor accuracy and thus the error bounds for individual sensors can be determined for each measurement.
• H. Qasem, Ch. Ament, L.M. Reindl
  A new Particle Filter for Localization of a Mobile Base Station Based on Microwave Backscatter
  2006 WPNC’06, Hannover 3rd Workshop on Positioning, Navigation and Communication 2006, pages: 37 - 46
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  Abstract

  This work presents an improved particle filter algorithm for a precise measurement of the local position of a mobile target. The presented measurement system consists of a mobile radar base station to be tracked and several active transponders located at predefined points of the working area. The system measures the range between the transponders and the base station like Frequency Modulated Continuous Wave (FMCW) radar by comparing the instantaneous frequencies of the transmitted and received signals, which has the advantage that the line of sight between the transponders and the base station is not always necessary and the data association problem can be completely avoided. It provides also the radial velocity of the base station to the respective transponder operates in the 5.8 GHz ISM band and can handle measurements up to 369 per μs within a few centimetres accuracy. In this paper we examine four data sets collected using this system. For each data set the base station traversed a repeating path for approximately five hours at different speeds. Range and range measurements to four transponders were collected through out the experiment each time with different distribution of the transponders. The developed particle filter is used to localise the base station after performing a detailed analysis of the noise inherent in the received ranges. Moreover, the noise sources are characterised and a noise model is developed to process the data with the particle filter algorithm.
• M. Köber, M. Hermle, J. Isenberg, M. Kasemann, H. Cárdenes, W. Warta
  Analysis of effects caused by parameter inhomogeneities with a 2-d-modelling tool based on circuit simulation
  2006 Proceedings of the 21st European Photovoltaic Solar Energy Conference, Dresden, Germany , page: 643
• U. Weik
  Anwendungen von anwenderprogrammierbaren Logikschaltungen (FPGAs) in der Messtechnik
  2006 Freiburg Sensoren und Messysteme 2006, ISBN: 3-8007-2939-3, VDI Verlag GmbH, Düsseldorf
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  Abstract

  FPGAs (Field Programmable Gate Arrays) gehören zu den anwenderprogrammierbaren Logikschaltungen. Diese bestehen aus verschiedenen digitalen Schaltungsteilen wie Gattern, Flipflops, Speicherblöcken und komplexeren Strukturen, deren Gesamtfunktion durch den Entwickler programmierbar ist. Sie haben mittlerweile Komplexitäten erreicht, die ohne Probleme das Integrieren von Software-Prozessorkernen (Softcores) ermöglichen. Bei diesen werden die im FPGA vorhandenen Logik-Ressourcen für den Aufbau des Prozessorkernes verwendet. Vorgestellt werden die typischen Entwicklungsschritte für die Integration eines kleinen Software-Prozessorkernes, der Anschluss der in der Messtechnik benötigten Peripherie-Schaltungen sowie eine Erläuterung der Ergebnisse.
• Grohe, A., Fleischhauer, B., Preu, R., Glunz, S. W., Willeke, G. P
  Boundary Conditions for the Industrial Production of LFC Cells
  2006 Proc. of the IEEE 4th World Conference on Photovoltaic Energy Conversion, Hawaii, USA
• Grohe, A., Catoir, J., Fleischhauer, B., Preu, R., Glunz, S. W., Willeke, G. P. Schneiderlöchner, E., Lüdemann, R., Liu, J., Schramm, S., Trassl, R., Wieder, S.
  Boundary Conditions for the Industrial Production of LFC Cells: Results from the Joint Project INKA
  2006 Proc. of the 21st European Photovoltaic Solar Energy Conference, Dresden, Germany, WIP-Munich
• D. Mastela, L.M. Reindl, L. Wiebking, L. Zander
  Development of a Cylindrical Microstrip Phased Array Antenna for a Radio Tracking System
  2006 March 6-8, New York IEEE Intern. Workshop on Antenna Technology, Small Antennas and Novel Metamaterials, pages: 381 - 383
• T. Jäger, M. Hobler, P. Sulzberger, F. Timmler
  Energieautarke Transpondersysteme für die Zustandsüberwachung rotierender Komponenten von Motorfrässpindel
  2006 Frankfurt Proc. of 4. GMM-Workshop Energieautarke Sensorik, ISBN 3-8007-29873, VDE Verlag Berlin GmbH
• E. Mackensen
  Energieversorgung, Energiemanagement und Lebensdauer autarker, drahtloser Mikrosensoren und –aktoren
  2006 Freiburg Sensoren und Messsysteme 2006, VDI Verlag GmbH, Düsseldorf – ISBN 3-8007-2939-3, ITG / VDE / VDI
• D. Mastela, L.M. Reindl, L. Wiebking, T. Zander
  Improving FMCW-based object tracking using phased array antennas combined with sigma-point Kalman filters
  2006 Karlsruhe Proceedings of German Microwave Conference
• A. Kiefer, L. M. Reindl
  Low-Cost-Sensorik an Hochtemperatur-Aktoren über Power-Line Communication
  2006 13. ITG/GMA-Fachtagung 13.-14. März, Freiburg/Breisgau Sensoren und Messsysteme 2006, pages: 127 - 129
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  Abstract

  Leistungsaktoren in verfahrenstechnischen Anlagen sind oft hohen Betriebstemperaturen ausgesetzt. Notwendige Sensorik wird üblicherweise so angeordnet, dass möglichst nur die eigentlichen Sensoren den hohen Temperaturen ausgesetzt sind und die zugehörige Messelektronik weiter entfernt angeordnet ist. Nachteilig ist der dadurch anfallende Aufwand an zusätzlicher Verkabelung. Hier wird ein Messsystem vorgestellt, bei welchem die komplette Sensorik und Messelektronik in den Leistungsaktor integriert ist und die Datenübertragung mittels Power Line Communication als Punkt-zu-Punkt-Verbindung zum zugehörigen Steuergerät stattfindet. Hierdurch werden keine zusätzlichen Leitungen mehr benötigt. Die erhöhten Anforderungen an die Elektronik, insbesondere durch den Einsatz bei hoher Umgebungstemperatur und bei gleichzeitiger Forderung einer Low-Cost-Lösung werden diskutiert und Lösungen präsentiert. Das realisierte Messsystem und seine Komponenten werden dargestellt und die Kosteneinsparungen aufgezeigt.
• M. Loschonsky, D. Eisele, L.M. Reindl
  Mass Sensitive Thin Film Bulk Acoustic Wave Resonators
  2006 Miami Proceedings of the IEEE International Frequency Control Symposium Miami 2006, pages: 111 - 116
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  Abstract

  The mass sensitive effect of RF-Filter technology based Film and Solidly-mounted Acoustic Bulk Wave single resonators (FBARs and SBARs) is investigated for metrological use. For a high resolution of a sensor system all systematical errors like cross temperature sensitivity must be eliminated. A high quality factor Q is needed for stable oscillating for minimizing statistical errors. Experiments using FBAR and SBAR single resonators have been carried out in a vapor deposition facility and thermal chamber to analyze mass and temperature sensitive effects. The usage of more than one resonant mode with distinct polarization might allow the compensation of cross sensitivities.
• D. Mastela, L.M. Reindl, T. Zander, L. Wiebking, M. Kawalkiewicz
  Multipath mitigation through cylindrical microstrip phased array antenna
  2006 Karlsruhe Proceedings of German Microwave Conference
• Granek, F., Hermle, M., Fleischhauer, B., Grohe, A., Schultz, O., Glunz, S. W., Willeke, G. P.
  Optimisation of Laser-Fired Aluminium Emitters for High Efficiency N-Type Si Solar Cells
  2006 Proc. of the 21st European Photovoltaic Solar Energy Conference, Dresden, Germany, WIP-Munich
• H. Qasem, L.M. Reindl
  Particle filter for localization of a mobile vehicle based on microwave backscatter
  2006 4-8 June, Mykonos, Greece Proc. 15th IST Mobile & Wireless Communications Summit
• H. Qasem, L.M. Reindl
  Precise wireless indoor localization with trilateration based on microwave backscatter
  2006 December, Florida, USA Proc. 8th IEEE Wireless and Microwave Technology (WAMICON 06)
• H. Qasem, L.M. Reindl
  Real time nonlinear indoor positioning with trilateration based on microwave backscatter
  2006 Bucharest, Romania Proc. 5th WSEAS International Conference on Non-linear Analysis , Non-linear Systems and Chaos (NOLASC '06)
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  Abstract

  We present two techniques for estimating accurately the position of a mobile base station in industrial environment with Trilateration. By eliminating the need to measure angles, trilateration uses only distance measurements to estimate position, which facilitate the implementation of real-time positioning systems like the Global Positioning System (GPS). Iterative linear least squares and nonlinear least squares estimators are implemented through simulation. We consider the minimization of the squares of errors, where the main difference depends on the linearity of the measurement equation which relates the coordinates to be estimated to the measured distance. The results obtained show that the nonlinear squares technique results in more accurate position estimates than linear least squares. Error distribution functions and histograms in both cases are also derived and analysed.
• R. Hauser, R. Fachberger, G. Bruckner, L.M. Reindl
  Tagging of Metallic Objects in Harsh Environments
  2006 13. GMA/ITG Fachtagung Sensoren und Messsysteme 2006, pages: 619 - 624
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  Abstract

  At present there are activities establishing radio frequency identification (RFID) systems allowing for tracking of goods worldwide. Solutions based on CMOS technology are limited to temperatures of 200°C. Furthermore, a metallic background usually restricts the reading distances to a few centimetres as a result of interference or even absorption of the interrogation signal. Surface acoustic wave (SAW) devices are known to operate stable up to several hundreds of degrees. Also a wireless readout over several meters is easily enabled, simply by connecting the component to an RF antenna. For all these reasons, SAW devices are ideally suited when measurements have to be performed in harsh environments. Yet when tagging of metallic objects is considered a particular design of the antenna part is required. In this work, a SAW-based ID system is presented allowing for tagging of metal objects exposed to harsh environments. Two types of transponders are described: (i) a SAW device mounted on a slot antenna, ideally suited for long distance tagging over several meters and functional up to 400°C. (ii) a SAW device moulded into a high temperature resistive polymer “pill” form, that can fully be integrated into a metal body. The system solution also includes a reader unit employing the FSCW principle operating in the ISM band from 2.4 GHz to 2.4835 GHz.
• R. Fachberger, G. Bruckner, R. Hauser, L.M. Reindl
  Wireless SAW based high-temperature measurement systems
  2006 Proc. 2006 IEEE Freq. Contrl. Symp., pages: 358 - 367
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  Abstract

  The paper exemplifies the development of a surface acoustic wave (SAW) temperature measurement system, showing the advantages of wireless data transmission and passive sensor operation. It includes results of research on lithium niobate, langasite and gallium-orthophosphate, three piezoelectrica used as substrate crystals for the SAW devices. Critical parameters, limits and prospects of the materials as well as technological issues concerning the metallization and the lifetime of reflective SAW delay lines are discussed. The packaging and assembly of high temperature (HT) stable transponders is explained. A slot antenna, a patch antenna and a dipole antenna, thus providing maximum flexibility for the sensor geometry, are investigated. A phase matching algorithm, enhancing the measurement resolution by two orders of magnitude compared to a conventional peak detection algorithm, is described. A fully integrated SAW temperature sensor system is presented, basing on a frequency modulated radar operating in the 2.45 GHz ISM band and designed for a world wide legal usage.
• R. Huber, T. Jäger
  Zustandsüberwachung mit Mikrosystemtechnik im Maschinenbau
  2006 RWTH Aachen Proc. of Aachener Kolloquium für Instandhaltung, Diagnose und Anlagenüberwachung AKIDA, ISBN 9810344-3-0

2005

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• J.H. Kuypers, D.A. Eisele, L.M. Reindl
  Design of wireless reflective delay line devices using the K-model
  2005 Japan Piezoelectric Material – Device Symposium
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  Abstract

  In this work we demonstrate the application of the K-Model [1][2] to the design of wireless devices based on reflective delay lines. The approach described is directly applicable to the development of ID-tags and tag based sensors. We will further present the simulation and experimental results for reflective delay line based tags fabricated on 128° LiNbO3 and operating at 2.45 GHz.
• T. Jäger
  Energieautarke Sensorik in Werkzeugmaschinen
  2005 Bayrisches Kompetenznetzwerk für Mechatronik, Augsburg Tagungsband Internationales Forum Mechatronik (ifm), ISBN 3-937002-03-0
• E. Mackensen, W. Kuntz, Cl. Müller
  Enhancing the Lifetime of Autonomous Microsystems in Wireless Sensor Actuator Networks (WSANs)
  2005 Barcelona Proceedings of the EUROSENSORS XIX Conference
• E. Mackensen, Cl. Müller
  Implementation of Reconfigurable Micro-Sensor Interfaces Utilizing FPAAs
  2005 4th IEEE international conference on sensors, Irvine Proceedings of the IEEE Sensors 2005
• E. Mackensen, W. Kuntz
  Power Aware Autonomous Microsystems for Wireless Sensor Networks
  2005 München Proceedings of the Wireless Congress
• Schneiderlöchner, E., Grohe, A., Fleischhauer, B., Hofmann, M., Glunz, S., Preu, R., Willeke, G.
  Status and advancement in transferring the laser-fired contact technology to screen-printed solar cells
  2005 Proc. of the 20th European Photovoltaic Solar Energy Conference, Barcelona, Spain,
• J.H. Kuypers, D.A. Eisele, L.M. Reindl
  The k-model - green's function based analysis of surface acoustic wave devices
  2005 Proc. 2005 IEEE Ultrasonics Symp., pages: 1550 - 1555
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  Abstract

  We have derived a model for the analysis of surface acoustic wave devices based on relating the surface potential adherent to surface acoustic waves propagating on a piezoelectric substrate and applied transducer potentials. Device structures are analyzed on the basis of the Green’s function, including end effects, electrical loading, mass loading effects, electrode resistance, dispersion, and propagation loss, leading to a 3-port matrix representation of single electrode cells. Cascading these matrices leads to the final sought after device response. The coupling to bulk waves is currently not taken into account. The model has been used to simulate and design 2.45 GHz SAW devices for wireless sensor applications, showing close agreement of simulation and measurement of fabricated devices. Results for a single-electrode interdigital transducer (IDT) with a designed centre frequency of 2441.75 MHz are compared and discussed. The measured equivalent circuit elements at the centre frequency for the SAW transducers fabricated on 128°YX-LiNbO3 compared to simulated results in brackets yielded 53.3 Ω (49.8 Ω), 0.76 pF (0.78 pF), and 5.57 nH (5.45 nH) for the input impedance, susceptance (static capacitance and acoustic susceptance), and computed parallel matching inductance. The deviation of simulated and measured centre frequency was found to be 0.14 %.
• E. Mackensen, Cl. Müller
  Universal Programmable Sensor Interface (UPSI) for Autonomous Microsystems
  2005 Nürnberg Proceedings of the Sensor + Test Conference
• L.M. Reindl
  Unwired SAW Sensors Systems
  2005 Yalta, Crimea, Russia International Conference on advanced optoelectronics and Lasers
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  Abstract

  Surface acoustic wave (SAW) devices can be used as identification and sensor elements (SAW transponders) for measuring physical, chemical and biological quantities such as temperature, pressure, torque, acceleration, humidity, etc. that do not need additional power supply for the sensor elements and may be accessed wirelessly. The complete wireless sensor system includes a transponder, consisting of an antenna wired to a SAW device, and a local reader unit, consisting of a radar transceiver linked to a signal processing and controlling unit. An RF burst transmitted by the radar transceiver is received by the passive SAW transponder. The passive transponder responses with an RF signal - like a radar echo, which can be received by the front-end of the local transceiver. Amplitude, frequency, phase, and time of arrival of this RF response signal carry information about the SAW reflec-tion and propagation mechanisms which in many cases can be directly attributed to the sensor effect for a certain measurand. Due to the high delay time of the SAW transponder in the order of a few μs, usually no intersymbol interferences (ISI) due to environmental reflections occur when the system operates in typical, i.e. harsh indoor/outdoor environments. The present work reviews the operating principle of such sen-sor systems and their state-of-the-art performance by way of a few examples which include the wireless measurement of tem-perature, pressure, torque, acceleration, tire-road friction, mag-netic field, and water content of soil.

2004

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• G. Kovacs, W. Ruile, M. Jakob, U. Rösler, E. Mayer(Garova), U. Knauer, H. Zottl
  A SAW duplexer with superior temperature characteristics for US-PCS
  2004 Proceedings of IEEE 2004 Ultrasonics Symposium, pages: 974 - 977
• S. Kamiya, J. Kuypers, A. Trautmann, P. Ruther, O. Paul
  Annealing Temperature Dependent Strength of Polysilicon Measured Using a Novel Tensile Test Structure
  2004 Maastricht Proceedings of the MEMS 2004
• L.M. Reindl, E. Mackensen
  Autarke, drahtlose Sensor-Aktor-Systeme - State of the Art
  2004 Ulm Gerotron Communication GmbH (Veranst.): Hochfrequenz- und Mikrowellen-Elektronik, Komponenten und Module - Workshop & Entwicklerforum
• E. Mackensen, W. Kuntz
  Autonomous Microsystems for Wireless Sensor-Actuator-Networks
  2004 Proceedings of the Wireless Congress 2004
• F. Kubat, W. Ruile, U. Rösler, L.M. Reindl
  Calculation of the SAW-induced distributions in an electrode of a SAW-device on LiTaO3
  2004 Montreal Proc. 2004 IEEE UFFC Joint Conference
  » show abstract« hide abstract
  Abstract

  Acoustomigration is a well-known phenomenon, which may occur in Surface Acoustic Wave (SAW)-devices operating at high driving levels. Based on previously published reports [1-3] about calculation of the acoustic power, dynamic stresses and displacements in a homogenous isotropic Al-layer for a given driving condition, we expand this method for the calculation of the SAW-induced stress in an electrode of a SAW-device. The quantitative calculation of this stress is based on the combination of the widely used P-Matrix based model, which yields the distribution of the potential power [2] for a given driving level and a FEM tool [4], which provides the relative stresses inside an electrode.
• L.M. Reindl, I.M. Shrena
  Drahtlose Messung der Temperatur mit OFW-Sensoren
  2004 VDE-Verlag GmbH, VDI/VDE-Gesellschaft
• L.M. Reindl, I.M. Shrena
  Drahtlose Messung der Temperatur mit OFW-Sensoren
  2004 Düsseldorf Sensoren und Messsysteme 2004, VDE-Verlag GmbH, ISBN 3-18-091829-2, VDI/VDE-Gesellschaft, volume: 1829
  » show abstract« hide abstract
  Abstract

  Oberflächenwellenbauelemente können als kabellose Sensorelemente ohne externe Stromversorgung, sogenannte OFW Transponder, eingesetzt werden, um physikalische Größen, wie etwa die Temperatur, zu messen. Ein derartiges kabelloses Sensorsystem besteht aus einem oder mehreren OFW Transpondern und einem Lesegerät. Eine Änderung der Temperatur bewirkt auf einigen OFW Substraten auch eine kleine Änderung der Geschwindigkeit der OFW, was wiederum das Antwortsignal des OFW Transponders beeinflusst. Durch eine Analyse des Laufzeitunterschieds zwischen einzelnen Impulsen des Antwortsignals erhält man eine grobe Abschätzung der Temperatur des OFW Transponders. Diese Information reicht aus, die Mehrdeutigkeit von ±2π in den Phasenunterschieden zu eliminieren, so dass zusätzlich die stetigen Phasen ausgewertet werden können. Durch diese Phasenauswertung erzielt man eine Genauigkeit der Temperaturmessung von ±0,2 °C.
• R. Hauser, L.M. Reindl, J. Biniasch
  Hochtemperaturtaugliche OFW-Marken zur Identifizierung eines Drucksensors
  2004 Düsseldorf Sensoren und Messsysteme 2004, VDE-Verlag GmbH, ISBN 3-18-091829-2, VDI/VDE-Gesellschaft
  » show abstract« hide abstract
  Abstract

  Ausgelöst durch die Notwendigkeit einer Identifizierung (ID) eines AVL Drucksensors in einem Verbrennungsmotor, wurden verschiedene Methoden untersucht. Die zu findende Lösung muss dabei vor allem den rauen Umgebungsbedingungen, die auf den nahe zur Brennkammer montierten Sensor einwirken, standhalten. Durch eine kleine Bauform soll dieses ID-Tag direkt im vorhandenen Sensorgehäuse integrierbar sein und sich durch eine entsprechende Robustheit gegen Stöße, Vibrationen, hohe Temperaturen und Temperaturgradienten auszeichnen. Darüber hinaus soll dieses Identifizierungssystem zu geringen Kosten und ohne aufwendige Änderungen am Sensor und der Signalkette realisierbar sein. Als Ergebnis dieser Untersuchung wurde eine Identifizierung mittels passiver OFW IDMarken entwickelt und erfolgreich getestet. Darüber hinaus erweist sich diese ID-Lösung als tauglich für den Einsatz in unterschiedlicher industrieller Umgebung.
• D.A. Eisele, L.M. Reindl
  Inductively coupled excitation and reading of crystal resonators for wireless temperature sensing
  2004 Linz, Austria International Symposium on Signals, Systems and Electronics
  » show abstract« hide abstract
  Abstract

  Temperature sensing is widely-used in industrial instrumentation, but entirely passive wireless solutions are limited. As discussed in literature some possible solutions are SAW sensors or sensor technology based on bulk acoustic resonators and microwave signals. This paper illustrates a new approach for close-coupling systems using low frequency crystal resonators and inductively coupled coils. We discuss in detail the energy and signal transmission for the excitation and reading duty cycle and consider our system performance.
• E. Mackensen, W. Kuntz
  Intelligente, autarke Mikrosysteme für drahtlose Sensor-Aktor-Netzwerke
  2004 VDE-Verlag GmbH, VDI/VDE-Gesellschaft
• E. Mackensen, W. Kuntz
  Intelligente, autarke Mikrosysteme für drahtlose Sensor-Aktor-Netzwerke
  2004 Düsseldorf Sensoren und Messsysteme 2004, VDE-Verlag GmbH, ISBN 3-18-091829-2, VDI/VDE-Gesellschaft
  » show abstract« hide abstract
  Abstract

  Der zunehmende Bedarf an Anwendungen, in denen Sensoren Messwerte erfassen, Aktoren angesteuert werden und eine Interaktion gefordert ist, führt zu der Herausforderung, intelligente, autarke Mikrosysteme zu realisieren. Damit ist es möglich, die Daten mehrerer Sensoren aufzunehmen, zu verarbeiten, mehrere Aktoren anzusteuern, mit einer großen Anzahl anderer Systeme drahtlos zu kommunizieren und eine lange Lebensdauer auf Grund eines niedrigen Energieverbrauchs zu erreichen. Zudem können damit drahtlose Sensor-Aktor- Netzwerke in verschiedensten Anwendungsbereichen wirtschaftlich implementiert werden. In diesem Beitrag werden die Anforderungen an die Architektur eines intelligenten, autarken Mikrosystems definiert und Möglichkeiten zur Realisierung vorgestellt. Außerdem werden die Resultate aus der Implementierung eines derartigen Mikrosystems präsentiert.
• L. Wiebking, L.M. Reindl, D. Mastela, M. Vossiek
  Local Positioning Radar
  2004 Hannover WPNC'04 proceedings
• R. Fachberger, J. Biniasch, G. Bruckner, C. Ruppel, R. Hauser, L.M. Reindl
  Properties of radio frequency Rayleigh waves on Langasite at elevated temperatures
  2004 Montreal Proc. 2004 IEEE UFFC Joint Conference
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  Abstract

  The properties of Rayleigh waves operating both at radio frequency (RF) and at high temperatures (HT) on Langasite crystal cuts with Euler Angles of (0°, 138.5°, 26.6°) and (0°, 30.1°, 26.6°) are investigated. By evaluating the frequency response of surface acoustic wave (SAW) test devices the SAW velocity, the coupling factor, and the propagation attenuation have been determined experimentally in a temperature range from 20 °C to 500 °C. The SAW devices could be operated up to frequencies of 3 GHz. However, considering a future sensor application a limiting factor is a strong increase of the acoustic losses in conjunction with frequency and temperature.
• L. Wiebking, D. Mastela, M. Glaenzer
  Remote Local Positioning Radar
  2004 Atlanta IEEE Radio and Wireless Conference Proceedings, pages: 191 - 194
• E. Mackensen, W. Kuntz, Cl. Müller
  Smart Wireless Autonomous Microsystems (SWAMs)
  2004 New Orleans, USA Proceeding of the Sensors For Industry Conference
  » show abstract« hide abstract
  Abstract

  Today a lot of different sensors and actuators are available which have an analog or digital, a standardized or not standardized interface. Many applications needs to measure sensor values, to control actuators and to interact between several sensors/actuators and other systems. Thus an intrinsic goal exists that the sensors and actuators can autonomously communicate with each other. A lot of applications are not suitable for wired communication. Hence there is an additional goal to realize the communication wireless. These goals lead to the challenge to implement Smart, Wireless, Autonomous Microsystems (SWAMs). Such a microsystem may capture the data of several sensors and control actuators. It will be intelligent and can communicate with a great number of other systems. Because the communication is wireless it is necessary that the SWAM is power aware to achieve a long lifetime. With SWAMs it is possible to build sensor actuator networks in the area of medical technology, environmental technology, process technology etc. This paper gives a survey about the requirements for the architecture of SWAMs. Then it will be pointed out, which feasibilities exist to realize such architectures. Finally the results from the implementation of such a microsystem will be presented and at the end of the paper novel applications will be showed.
• C. Eberl, R. Spolenak, F. Kubat, E. Arzt, A. Leidl, W. Ruile, O. Kraft, L.M. Reindl
  Ultra high cycle fatique in pure Al thin films and line structures
  2004 TMS Annual Meeting
• E. Mackensen, L.M. Reindl
  Wireless Passive SAW Identification Marks and Sensors
  2004 Springer, Yurish, S. Y.; Gomes, M. T.
• E. Mackensen, L.M. Reindl
  Wireless Passive SAW Identification Marks and Sensors
  2004 Curia, Portugal Smart Sensors and MEMS: Proceedings of the NATO ASI on Smart Sensors and MEMS 2003 ISBN 1-4020-2927-6, Springer / Yurish, S. Y.; Gomes, M. T.

2003

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• G. Bruckner, A. Stelzer, L. Maurer, J. Biniasch, L.M. Reindl, R. Teichmann, R. Hauser
  A high - temperature stable SAW identification tag for a pressure sensor and a low cost interrogation unit
  2003 Nürnberg, Germany SENSOR'03
• A. Stelzer, R. Hauser, L.M. Reindl, R. Teichmann
  A low-cost interrogation unit and signal processing for a saw identification-tag for a pressure sensor
  2003 June 22-27, Dubrovnik XVII Imedo World Congress Metrology in the 3rd Millennium
• M. Hara, J. Kuypers, T. Abe, M. Esashi
  Aluminium Nitride Based Thin Film Bulk Acoustic Resonators Using Germanium Sacrificial Layer Etching
  2003 Boston Proceedings of the Transducers 2003, pages: 1780 - 1783
• E. Mackensen, W. Kuntz
  Bluetooth - Die ideale drahtlose Datenkommunikation für intelligente, autarke Mikrosysteme
  2003 4. Bluetooth-Kongress
• E. Mackensen, W. Kuntz
  Bluetooth -und neue Low-Power-RF-Techniken für intelligente, autarke Mikrosysteme
  2003 5. Bluetooth-Kongress
• F. Kubat, W. Ruile, T. Hesjedal, J. Stotz, U. Rösler, L.M. Reindl
  Distribution of the dynamic strain and stress components within a layered film of SAW resonator on LiTaO3
  2003 Proc. 2003 IEEE Ultrasonics Symp.
  » show abstract« hide abstract
  Abstract

  Based on recent reports about the acoustical power distribution in SAW resonators we present an analytical method to determine the distribution of the dynamic strain and stress components in SAW resonators on LiTaO3. This enables us to calculate the absolute strain and stress values for each point in the layer of a resonator for any driving condition and frquency. The SAW resonator is described by a P-Matrix based model, which gives us the distribution of the potential power and the resulting energy density. For calculation of the relative strain and stress values we used the Partial Wave Method. Using the correlation between the total acoustic power and the energy density distribution normal to the substrate surface, we can calculate the strain and stress values for a given input power. For the direct experimental verification of our calculations we measured the SAW induced displacements as a function of input power.
• G. Bruckner, R. Hauser, A. Stelzer, L. Maurer, R. Teichmann, J. Biniasch, L.M. Reindl
  High - temperature stable SAW based tagging system for identifying a pressure sensor
  2003 Proc. 2003 IEEE Freq. Contrl. Symp.
  » show abstract« hide abstract
  Abstract

  Driven by the need for identifying an AVL pressure sensor inside of a combustion engine, various methods for this purpose have been examined. The solution found has to be compatible with the constraints placed by both the harsh environmental conditions acting on a sensor mounted close to the combustion chamber and the reading technique employed to monitor the data. Thus the final solution, preferably mounted inside of the pressure sensor, has to withstand shock, vibrations, high temperatures and temperature gradients, to provide a high isolation resistance and to fit into small size bore. Furthermore, the solution has to cope with additional demands such as low-costs or minor modifications of the sensor only
• R. Hauser, J. Biniasch, L.M. Reindl
  High High - temperature stability of LiNbO3 and Quartz based SAW Devices
  2003 Proc. 2003 IEEE Ultrasonics Symp.
• L.M. Reindl, I. Shrena, H. Richter, R. Peter
  High Precision Wireless Measurement of Temperature by Using Surface Acoustic Waves Sensors
  2003 Nürnberg, Germany Proc. 2003 IEEE Freq. Contrl. Symp.
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave devices can be used as wireless sensor elements (SAW transponders) for measuring physical quantities such as temperature, that do not need any power supply and may be accessed wirelessly. The complete wireless sensor system consists of such a SAW transponder and a local radar transceiver. An RF burst in the VHF/UHF region transmitted by the radar transceiver is received by the antenna of the SAW transponder. The passive transponder responses with an RF signal - like a radar echo - which can be received by the front-end of the local transceiver. The amplitude and phase of this RF response signal carry information on the positioning Surface acoustic wave (SAW) devices can be used as sensor elements that do not need any power supply and may be read out wirelessly. The reader unit performs a radar measurement of the impulse response of the SAW transponder via a high-frequency electromagnetic radio link. A temperature variation changes the SAW velocity and thereby the response pattern of the SAW device. By analyzing the time delay between backscattered pulses with different time delays we get a coarse estimation of the temperature of the SAW transponder. By using this information the ambiguity of ±2π in the phase differences between the pulses can be eliminated, which enables to an overall temperature resolution of ±0.2°C.
• T. Hesjedal, F. Kubat, J. Mohanty, W. Ruile, L.M. Reindl
  In-situ study of acoustomigration by scanning acoustic force microscopy
  2003 Proc. 2003 33rd European Microwave Conference
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  Abstract

  High-power operation of surface acoustic wave devices may lead to stress induced material transport, so-called acoustomigration. We used Scanning Acoustic Force Microscopy (SAFM) to study acoustomigration of metal structures in-situ, i.e. during the high-power loading of the device. SAFM allows for the simultaneous measurement of the acoustic wavefield and the topography with submicron lateral resolution. We present acoustic wavefield and topographic image sequences giving a clear insight into the nature of the film damage on a submicron scale. The 900 MHz test structures were fabricated on 36°YX-LiTaO3 incorporating 420 nm thick Al electrodes. By correlating the acoustic wavefield mapping and the local changes in the topography point-by-point, already the initial changes of the granular structure that lead to acoustomigration can be visualized.
• M. Hara, J. Kuypers, T. Abe, M. Esashi
  MEMS Based Thin Film 2 GHz Resonator for CMOS Integration
  2003 Philadelphia Proceedings of the IMS Symposium 2003, pages: 1797 - 1800
• T. Jäger, D. Werner, A. Stock
  Manufacturing Engineering for Nanoproduction
  2003 Proc. of Int. Conf. on MicroNano Integration, ISBN 3-540-20252-8, Springer-Verlag, pages: 257 - 258
• G. Villanueva, P. Hartogh, L.M. Reindl
  Microwave Technologies for SOFIA's High Resolution Spectrometer
  2003 Proc. 2003 33rd European Microwave Conference
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  Abstract

  Improvements in the resolution and the dynamic range of the CTS (Chirp Transform Spectrometer) were achieved thanks to the development of microstrip devices, mathematical modeling of microwave components and the use of adaptive digital technologies. CTS is part of GREAT (German REceiver At Terahertz frequencies), a first-generation dual-channel heterodyne instrument for high-resolution spectroscopy aboard the airborne observatory SOFIA (Stratospheric Observatory for Infrared Astronomy).
• M. Hara, J. Kuypers, T. Abe, M. Esashi
  On-chip 2 GHz AlN TFBAR (Jap.)
  2003 Piezoelectric Device Symposium (Jap.), pages: 43 - 46
• L. Wiebking, M. Vossiek, L.M. Reindl, M. Christmann, D. Mastela
  Precise Local Positioning Radar with implemented Extended Kalman filter
  2003 Munich Proc. 33rd European Microwave Conference (EUMC), pages: 459 - 462
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  Abstract

  In this paper a novel solution for the tracking of a moving object based on Kalman-filtering is presented. The radar system applied measures the range between transponders and the radar base station similar to a frequency modulated continuous wave radar with active reflectors by comparing the instantaneous frequency of transmitted and received signal. It also provides the range rate (radial velocity) of the base station to the respective transponder. To estimate a three-dimensional position from a set of range measurements a Trilateration of minimum three ranges can be calculated. Since the measured ranges and range rates are distorted by noise sources ill conditioned angles of cut between the intersecting circular arcs lead to distorted position estimates. Furthermore multi path distorted range measurements can hardly be recognized and thus lead to heavy distortion of the estimate. A model-based filter allows taking past measurements into account. This reduces the error of the estimated position. The linear Kalman Filter (KF) is a recursive formulation of a model-based filter. Using an extended version of the Kalman filter (EKF) the object position can be estimated directly from ranges and range rates once the filter is initialized. This paper describes an EKF for the estimation of a three dimensional position from ranges and range rates. A gating method to filter out multi path distorted measurements is proposed. The Local Positioning Radar was tested in a steelwork environment and the obtained results (accuracy, deviation, repetition rate) are presented.
• L.M. Reindl
  Wireless Passive SAW Identification Marks and Sensors
  2003 Stiftung Caesar, 16.-18.7.2003, Bonn, Germany 4. caesaruim
• E. Mackensen, L. M. Reindl
  Wireless Passive SAW Identification Marks and Sensors - Surface Acoustic Wave Devices
  2003 Povoa de Varzim / Portugal Smart Sensors and Mems. Tutorials and Poster Abstracts

2002

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• J.H. Kuypers, T. Ono, M. Esashi
  Aluminium Nitride based Piezoelectric Microactuators
  2002 Kyoto, Japan Proceedings of the 19th Sensor Symposium 2002, pages: 459 - 464
• E. Mackensen
  Drahtlose Datenkommunikation für intelligente autarke Mikrosysteme
  2002 2. GMM-Workshop Energieautarke Sensorik
  » show abstract« hide abstract
  Abstract

  Kern des Beitrags ist die Vorstellung der in Frage kommenden und derzeit verfügbaren drahtlosen Kommunikationsmöglichkeiten für autarke Mikrosysteme. Unter intelligenten, autarken Mikrosystemen versteht man Mikrosysteme, welche die Daten mehrerer Sensoren aufnehmen und verarbeiten können, mehrere Aktoren ansteuern können, eine gewisse Intelligenz besitzen und energieautonom sind. Grundlegende Forderung an ein autarkes Mikrosystem ist, mit einer großen Anzahl anderer Systeme kommunizieren zu können. Der Anwendungsbereich solcher autarker Mikrosysteme ist heute vielfältig: Medizintechnik, Umwelttechnik, Prozesstechnik, ... Ein System ist nur dann wirklich autark, wenn man statt kabelgebundener Kommunikation drahtlose Kommunikation in diesen Systemen einsetzt. Die Schwerpunkte bei dem Vergleich der möglichen Kommunikationstechniken liegen dabei auf der Miniaturisierung, dem Leistungsverbrauch, der Übertragungssicherheit, der Übertragungsrobustheit, der Interoperabilität und den Kosten der entsprechenden Techniken. Es soll aufgezeigt werden, welche der vorgestellten Kommunikationsmöglichkeiten sich am Besten zur Kommunikation in autarken Mikrosystemen eignen.
• L.M. Reindl
  Messung physikalischer Größen mittels funkauslesbarer passiver OFW-Sensoren
  2002 Dresden, Germany GMM/ITG-Workshop „Energieautarke Sensorik“ am 6. / 7. Juni 2002
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  Abstract

  Mittels Oberflächenwellen (OFW)-Bauelemente werden miniaturisierte mikroakustische Identifikations- und Sensorelemente (Transponder) ermöglicht, die ohne eigene Stromversorgung telemetrisch abgefragt werden können (OFW-Funksensorik). Die Transponder speichern die ABfragesignale, bis alle Umgebungsechos abgeklungen sind. Dann wird ein charakteristisches Antwortmuster des Transponders zum Lesegerät zurückgestrahlt. Identifikationsmarken antworten dabei mit ihrem charakteristischen Identifikationsmuster. Im Falle der Funksensoren wirkt die physikalische oder chemische Messgröße auf die Ausbreitungseigenschaften der OFW ein und verändert so das Antwortmuster. In dem Beitrag wird das Funktionsprinzip dieser Transponder erläutert. Als Anwendungsbeispiele werden Identifikationsmarken sowie Sensoren für Temperatur, Druck, Beschleunigung, Drehmoment, Magnetfelder und Bodenfeuchte, sowie ein Sensor zur Ermittlung des Reibbeiwerts zwischen einem Kfz-Reifen und der Fahrbahn während der Fahrt gezeigt.
• F. Kubat, W. Ruile, L.M. Reindl
  P-Matrix based calculations of the potential and kinetic energy in resonating SAW-structures
  2002 Proc. 2002 IEEE Ultrasonics Symp.
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  Abstract

  Acoustomigration of metal structures is a phenomenon which may occur in Surface Acoustic Waves (SAW) devices operating at high power levels. This may deteriorate the performance or can even destroy the SAW device. Acoustomigration is caused by stored acoustic energy, which is very high in resonating structures with good quality factors. We developed a P-Matrix based model to calculate the stored energy in arbitrary SAW structures. We present in detail a method for determination of the total power distribution and the kinetic and potential power and their relative position within in the structure. From these calculations we derive the amplitudes of displacements and stress and visualize the corresponding time behavior in resonating and non-resonating structures. The acoustic patterns found experimentally are in excellent agreement with the calculated results.
• L.M. Reindl
  SAW-Based Radio Tag and Sensor Systems
  2002 January 28-29, Tokyo, Japan Proc. International Conference on New Piezoelectric Materials and High Performance Acoustic Wave Devices, pages: 71 - 78
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices can be used as identification and sensor elements (SAW transponders) for measuring physical, chemical and biological quantities such as temperature, pressure, torque, acceleration, humidity, etc. that do not need additional power supply for the sensor elements and may be accessed wirelessly. The complete wireless sensor system includes a transponder, consisting of an antenna wired to a SAW device, and a local reader unit, consisting of a radar transceiver linked to a signal processing and controlling unit. An RF burst transmitted by the radar transceiver is received by the passive SAW transponder. The passive transponder responses with an RF signal - like a radar echo, which can be received by the front-end of the local transceiver. Amplitude, frequency, phase, and time of arrival of this RF response signal carry information about the SAW reflection and propagation mechanisms which in many cases can be directly attributed to the sensor effect for a certain measurand. Due to the high delay time of the SAW transponder in the order of a few µs, usually no intersymbol interferences (ISI) due to environmental reflections occur when the system operates in typical, i.e. harsh indoor/outdoor environments. The present work reviews the operating principle of such sensor systems and their state-of-the-art performance by way of a few examples which include the wireless measurement of temperature, pressure, torque, acceleration, tire-road friction, magnetic field, and water content of soil.

2001

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• L.M. Reindl
  Messung elektrischer und nichtelektrischer Größen mit passiven Funktranspondern
  2001 Technische Universität Clausthal, Germany Informationstechnologie, Grundlagen und Anwendungen, Beiträge zum Tag der Forschung 25. Mai, pages: 26 - 27
• L.M. Reindl, A. Kirmayr
  Radio Readable Water Content Sensor System Using Passive SAW Transponders
  2001 Linz, Austria Proc. 3rd International Workshop on Commercial Radio Sensor and Communication Techniques ISBN: 3-85487-276-3, pages: 82 - 87
  » show abstract« hide abstract
  Abstract

  A sensor system for remote measurement of water content in sandy soil was developed, using a passive SAW transponder. Information from this sensor can be obtained by a reader device via a radio link operating in the European 434 MHz ISM-band. The SAW device contains a reflective delay line with four electro-acoustic transducers. One transducer is connected to an external antenna to pick up the RF request signal from the reader device and to send back a RF response. The second transducer operates as a reflector. The bus bars of this transducer are connected with two measuring rods through an electrical transmission line. These rods can be inserted into sandy soil. The final two transducers operate as reflectors and are included for reference purposes. The transmission line and the two rods spanning the sand-water-mixture have a characteristic impedance Zload, which loads the second transducer. Changes in the soil water content are observed as a change of the total permittivity due to the high permittivity of free water, which in turn affects Zload as well. The amplitude and phase of the acoustic reflection at the second transducer changes due to this variation of the terminating Zload. This then results in a difference in attenuation and phase of the corresponding peak in the time domain. Thus, the RF response of the sensor carries information about the water content between the rods, which therefore can be detected by and evaluated in the reader unit.
• A. Koppler, M. Huemer, L.M. Reindl, A. Springer, R. Weigel
  Single Carrier Transmission with Frequency Domain Equalization: A Comparison with Hiperlan/2 like OFDM Systems
  2001 Vienna, Austria Paper No. 36
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  Abstract

  In this paper, we compare the performance of a single carrier system with frequency domain equalization (SC/FDE) with an OFDM (Orthogonal Frequency Division Multiplexing) system as described in the Hiperlan/2 and IEEE 802.11a standards. We give an explanation of the SC/FDE concept which proves to have a couple of similarities to OFDM systems. We present bit error simulation results for the implemented SC/FDE system for uncoded as well as for channel-coded data in typical indoor multipath environments. Our results indicate that the proposed concept achieves similar bit error rate performance as a Hiperlan/2 or IEEE 802.11a like OFDM system, while the analog hardware requirements are much more moderate compared to OFDM systems.
• L.M. Reindl
  Theory of Wireless SAW Sensor Systems
  2001 Linz, Austria Proc. XI. International Symp. on Theoretical Electrical Engineering, August 19 – 22 ISBN: 3-9501491-0-4
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  Abstract

  Surface acoustic wave (SAW) devices can be used as identification and sensor elements that do not need any power supply and may be requested wirelessly (transponders). Such a transponder picks up an electromagnetic request signal and stores it until all echoes caused by multi-path propagation have died away. Then, a characteristic response signal is returned to the interrogator unit. Identification marks respond with their nonchanging identification pattern. In radio-link sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. This paper surveys the operating principle of such sensors systems and the state-of the-art performance of the SAW transponders.
• A. Stelzer, G. Schimetta, L.M. Reindl, A. Springer, R. Weigel
  Wireless SAW-Sensors for Surface and Subsurface Sensing Applications
  2001 San Diego, California, USA, July 29 - August 3 Proceedings of SPIE’s 46th Annual Meeting, International Conference on Subsurface Sensing Technologies and Applications III, volume: 4491
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave (SAW) devices, used as filters or diplexers, are well established components in communications applications like in mobile handsets or television sets. The characteristics of SAW devices make them also well suitable for the application of wireless sensors or wireless identification tags. A great advantage of SAW sensors is their completely passive operation without the need for additional power supplies. SAW sensors can be designed to sense several physical or chemical quantities like temperature, pressure, stress, or gas concentration. During operation of the wireless sensor the energy delivered from an RF pulse sent by an interrogation unit is picked up by the antenna, stored in the surface acoustic wave, modified by the sensor effect and is finally transmitted back to the interrogation unit. In this paper the basic operating principles of SAW devices are reviewed and two applications, a state-of-the-art tire pressure sensor and a moisture sensor, are presented.
• L.M. Reindl, R. Steindl, Ch. Hausleitner, A. Pohl, G. Scholl
  Wireless passive radio sensors
  2001 Proceedings SENSOR ´2001, volume: 1, pages: 331 - 336
  » show abstract« hide abstract
  Abstract

  Surface acoustic wave devices can be turned into identification and sensor elements (SAW transponders) for measuring physical quantities such as temperature, pressure, torque, acceleration, humidity, etc. that do not need any power supply and may be accessed wirelessly. The complete wireless sensor system consists of such a SAW transponder and a local radar transceiver. An RF burst in the VHF/UHF region transmitted by the radar transceiver is received by the antenna of the SAW transponder. The passive transponder responses with an RF signal - like an radar echo - which can be received by the front-end of the local transceiver. Amplitude, frequency, phase and time of arrival of this RF response signal carry information about the SAW reflection and propagation mechanisms which in many cases can be directly attributed to the sensor effect for a certain measurand. Due to the high delay time of the SAW transponder in the order of some μs, usually no intersymbol interferences due to environmental echoes occur. The present work reviews the operating principle of such sensor systems and their state-of-the-art performance by way of some examples which include the wireless measurement of temperature, pressure, torque, acceleration, magnetic field, and water content of soil.

2000

 back to the year overview

• R. Koller, W. Gugler, A. Springer, R. Weigel, L.M. Reindl
  A SAW-Based High-Speed Spread-Spectrum WLAN using Chirp - π/4-DQPSK Modulation
  2000 Proc. IEEE Ultrasonics Symp., pages: 367 - 370
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  Abstract

  A high data-rate wideband chirp spread spectrum system for indoor communication is implemented. The use of chirp signals with the well known pulse compression technique makes the system extremely robust and therefore suitable for applications in industrial environment. By using π/4-DQPSK modulation and overlapping chirp signals we get data rates up to 70Mbps. There is no need for sophisticated digital signal processing due to the use of surface acoust,ic wave (SAW) filters for the generation and filtering of the chirp signals. Production tolerances, temperature drift, and other system imperfections are shown to be eit,her negligible or can easily be tracked. Simulat,ion results reveal that, the limiting factor for the data rate is intersymbol interference caused by multipath propagation. A simple hardware demonstrator validates the simulation results.
• M. Huemer, L.M. Reindl, A. Springer, R. Weigel
  Frequency Domain Equalization of Linear Polyphase Channels
  2000 Tokio IEEE Vehicular Technology Conf. (VTC) 2000, volume: 3, pages: 1698 - 1702
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  Abstract

  In this paper, we consider the problem of linear equalization of polyphase channels and its implementation in the frequency domain. These channels may result from oversampling the single output of a transmission channel or/and by receiving multiple outputs of an antenna array. From the polyphase representation of the fractionally spaced channels/equalizers we derive a novel low complexity frequency domain implementation structure for optimum infinite-length equalizers. As an example we apply the concept to a high speed wireless indoor communication system. The digital baseband processing requirements are considered and simulation results for typical multipath channel conditions are presented.
• M. Huemer, L.M. Reindl, A. Springer, R. Weigel
  Frequency Domain Equalization of Multiple FIR Channels Using Oversampling and/or Multiple Antennas
  2000 Paris, Frankreich Proceedings of the European Conference on Wireless Technology (ECWT 2000), pages: 203 - 206
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  Abstract

  In this contribution we consider the problem of linear equalization of multiple FIR (finite impulse response) channels and its implementation in the frequency domain. These channels may result from oversampling the single output of a transmission channel and/or by receiving multiple outputs of an antenna array. From the polyphase representation of the channels/equalizers we derive a novel low complexity frequency domain implementation structure for optimum linear equalization combined with antenna diversity. As an example we apply the concept to a high speed wireless indoor communication system. The digital baseband processing requirements are considered and simulation results for typical multipath channel conditions are presented.
• L.M. Reindl, G. Scholl, F. Schmidt
  Funksensorik und Identifikation mit OFW-Sensoren
  2000 Sensoren und Meßsysteme 2000, 10. GMA /ITG Fachtagung, volume: 1530, pages: 799 - 810
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  Abstract

  Durch Oberflächenwellen (OFW)-Bauelemente werden neuartige Identifikations- und Sensorelemente (Transponder) ermöglicht, die funkauslesbar und passiv sind. Die Transponder speichern die Abfragesignale, bis alle Umgebungsechos abgeklungen sind. Dann wird ein charakteristisches Antwortmuster des Transponders zum Abfragegerät zurückgestrahlt. Identmarken antworten dabei mit ihrem charakteristischen Identifikationsmuster. Im Falle der Funksensoren wirkt die physikalische oder chemische Meßgröße auf die Ausbreitungseigenschaften der OFW ein und verändert so das Antwortmuster. In dem Beitrag wird das Funktionsprinzip dieser Transponder erläutert. Als Anwendungsbeispiele werden Identmarken für Bahnanwendungen, die Messung der Temperatur auf einer Bremsscheibe und auf einem Läufer eines Elektromotors gezeigt, die Messung des Reifendrucks und des Reibbeiwertes zwischen einem Kfz-Reifen und Fahrbahn während der Fahrt, ein Stromsensor und ein Sensor zur Ermittlung der Bodenfeuchte gezeigt.
• M. Huemer, C.C.W. Ruppel, L.M. Reindl, A. Springer, R. Weigel
  Single Carrier Transmission with Frequency Domain Equalization for Ultrabroadband Communication Systems
  2000 Galway, Ireland The Book of Visions 2000 - Visions of the Wireless World, pages: 70 - 72
• A. Springer, W. Gugler, M. Huemer, L.M. Reindl, C.C.W. Ruppel, R. Weigel
  Spread Spectrum Communication using chirp signals
  2000 Germany Proceedings of the EuroComm 2000, pages: 166 - 170
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  Abstract

  We report on the use of broadband chirp signals for spread spectrum systems for indoor applications. The presented system concepts make use of chirp transmission and pulse compression. Different modulation schemes for chirp signals resulting in different system performance and complexity are compared in terms of bit error rate for the AWGN channel and for frequency selective indoor radio channels. We present simulations and measurement results from demonstrator systems which use surface acoustic wave (SAW) devices for the generation and matched filtering of the chirp signals. RF and IF frequency and transmission bandwidth of the presented systems are 2.4 GHz 348.8 MHz and 80 MHz, respectively. Due to the processing gain of 16 dB - made possible by the use of SAW devices - and the large transmission bandwidth the system is insensitive against frequency selective fading, CW interference and noise.

1999

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• M. Huemer, L.M. Reindl, C.C.W. Ruppel, A. Springer, R. Weigel
  A new SAW-based OFDM receiver concept
  1999 Anaheim, USA Proc. 1999 IEEE MTT-S International Microwave Symp. ISSN 0149-654X, ISBN: 0-7803-5135-5, pages: 1847 - 1850
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  Abstract

  We report on a new SAW (Surface Acoustic Waves)-based receiver concept for OFDM (Orthogonal Frequency Division Multiplexing) that is suitable for wireless high data rate indoor applications. We give a brief system overview and present simulation results of the data throughput. The simulation parameters are adapted to the proposed physical layer specifications of the IEEE 802.11 Wireless Local Area Network (WLAN) and the European ETSI / HIPERLAN standardization groups. In both groups OFDM has been chosen for the physical layer in the high data rate WLAN systems in the 5 GHz ISM band. Since costly high speed digital signal processing is necessary for today’s high data rate requirements we propose a receiver concept with a SAW chirp Fourier transform.
• A. Pohl, R. Steindl, L.M. Reindl
  A new generation of passive radio requestable SAW sensors for ultrafast measurements
  1999 Proc. 16th IEEE Instrumentation Measurement Technology Conf., IMTC/99, pages: 1728 - 1733
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  Abstract

  In this paper we discuss surface acoustic wave sensors for the measurement of dynamic measurands. The sensor types and the principles of effecting by the measurand are described. For non-stationary measurands, terms like bandwidth, resolution and error limits are discussed, boundaries are given. A new method of SAW radio sensors is introduced, capable for high speed measurements. Dynamic parameters are estimated, experimental results are given for these new SAW sensor devices.
• M. Brandl, A. Pohl, F. Seifert, L.M. Reindl
  Fast adaptive interference cancellation in chirp spread spectrum systems
  1999 Global Telecommunications Conference vol.4, pages: 2218 - 2222
• M. Huemer, L.M. Reindl, A. Springer, R. Weigel
  Implementation Aspects on Single Carrier Transmission with Frequency Domain Equalization
  1999 Technical University of Hamburg-Harburg 4. OFDM-Fachgespräch and 1st Int. OFDM-Workshop, pages: 18/1 - 18/4
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  Abstract

  In this contribution we consider single carrier systems with frequency domain equalization (SC/FDE) for high data rate mobile indoor communications. We discuss different FDE implementation structures which prove to have a couple of similarities to OFDM (Orthogonal Frequency Division Multiplexing) systems. The digital baseband processing requirements are considered and simulation results for typical channel conditions are presented.
• A. Pohl, R. Steindl, L.M. Reindl
  Measurements of vibration and acceleration utilizing SAW sensors
  1999 Nürnberg , Germany SENSOR'99 Vol.2, pages: 53 - 58
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  Abstract

  In recent years, SAW devices became important for sensor purposes. SAW sensors are applied as well as wired sensor elements in active circuits and as remote passive devices. For wireless measurements, three types are available today, shown in the paper. An estimation of the measurement's dynamic and bandwidth is given. Utilizing SAW delay lines and resonators, the measurement of vibration and acceleration is presented. Experimental results are shown.
• A. Pohl, L.M. Reindl
  New passive sensors
  1999 Proc. 16th IEEE Instrumentation and Measurement Technology Conf., IMTC/99, pages: 1251 - 1255
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  Abstract

  In this paper, a new principle for passive radio requestable sensors is introduced. The currently available passive mostly use time division access to the radio channel for the remote readout In a different manner, the proposed sensors utilize frequency division access, achieved by nonlinearity of the passive sensor, consisting of a semiconductor device such as a diode and a passive impedance. The information is modulated due to the cross correlation effect. To evaluate the information, coherent demodulation is done.
• W. Hosp, D. Zittlau, M. Prenninger, L.M. Reindl, A. Pohl, R. Steindl
  Passive OFW Funksensorik für den "intelligenten" Reifen
  1999 Hannover, Germany 7. VDI Fachtagung Reifen, Fahrwerk, Fahrbahn
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  Abstract

  With the realisation of an "intelligent" tyre, that means a tyre which is able to give informations about its actual state, there will be an increase of safety and vehicle stability. This target was the starting point for Siemens Automotive to develop SAW radio sensor systems for the tyre. The sensors give actual values for friction, pressure and temperature to a control unit. The evaluation of the friction coefficient is working with the determination of the deformation of a profile element in the tyre.The actual state of the development demonstrates that the detection and transmission of the profile deformation by a SAW sensor is possible. The realisation of the SAW tyre sensors will open a way to optimize the slip control and the vehicle stability systems of the car and also enable future driver assistance systems.
• L.M. Reindl, C.C.W. Ruppel, A. Kirmayr, N. Stockhausen, M. Hilhorst
  Passive Radio Requestable SAW Humidity Sensor
  1999 Proc. 1999 IEEE Ultrasonics Symp., pages: 461 - 466
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  Abstract

  Using a SAW reflective delay line a new passive sensor for a remote measurement of the water content in sandy soil was built up. The system operates in the European 434 MHz ISM-band and consists of a request unit and a passive sensor connected by a radio link to the request unit. The SAW device is fabricated on LiNbO3, YZ-cut, and mounted and sealed in a standard DIL 16 package. The device includes four electro-acoustic transducer (IDTs), whereby three of them are used as reflectors. One transducer is connected to an external antenna to pick up the RF request signal of the request unit and to radiate back the RF response. Two reflectors are used for reference purposes. The bus bars of the median reflector are connected to an electrical transmission line with two rods added to their end. The rods are put into sandy soil. Together, the transmission line and the two rods with the sand-water- mixture between them have a characteristic impedance Zload, which terminates the second transducer and affect the amplitude and phase of the acoustic reflection. A change of the water content of the soil changes Zload due to the high permitivity of free water. The amplitude and phase of the acoustic reflection at the second transducer changes due to a variation of the terminating Zload, which appears in a different attenuation and phase of the corresponding peak in the time domain. Thus the RF response of the sensor carries the information of the water content between the rods, which therefore can be detected and evaluated in the request unit.
• L.M. Reindl, R. Steindl, A. Pohl, J. Hornsteiner, E. Riha, F. Seifert
  Passive Surface Acoustic Wave Sensors for Temperature and other Measurands
  1999 Netherlands Proc. Tempmeko 99, pages: 424 - 429
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  Abstract

  Surface acoustic wave (SAW) devices can be turned into novel sensor elements (transponders) that do not need any power supply and may be interrogated wirelessly. Such a transponder picks up an electromagnetic request signal and stores it until all echoes caused by multi-path propagation have faded away. Then, a characteristic response signal is retransmitted to the interrogator unit. In radio sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. This contribution surveys the operating principle of such temperature sensors and their state-of-the-art performance.
• M. Huemer, A. Koppler, C.C.W. Ruppel, L.M. Reindl, A. Springer, R. Weigel
  SAW Based Chirp Fourier Transform for High Data Rate Indoor OFDM Transmission
  1999 Proc. 1999 IEEE Ultrasonics Symp., pages: 373 - 376
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  Abstract

  We report on a new SAW based OFDM (Orthogonal Frequency Division Multiplexing) receiver concept for wireless indoor applications. We propose the use of the analog SAWchirp Fourier transform which replaces the digitally implemented FFT (Fast Fourier Transform) of conventional receiver concepts. These analog processors feature real time signal processing and so the amount of costly high speed digital signal processing is significantly reduced.
• F. Seifert, A. Pohl, R. Steindl, L.M. Reindl, M.J. Vellekoop, B. Jakoby
  Wireless interrogable acoustic sensors
  1999 Proc. 1999 Joint Meeting 13th Europ. Frequ. and Time Control Symp.
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  Abstract

  A survey is given on wirelessly interrogable passive surface acoustic wave (SAW) sensors. Three types of SAW devices are discussed and classified as to their function in remote sensing of measurands (e.g. temperature, mechanical strain, stress ec.): Type I: transit time sensors, type II: SAW delay lines for wireless evaluation of remote conventional sensors and type III: SAW resonators. Efficient and successfully proven methods of wireless interrogation and evaluation are presented and some applications briefly mentioned.

1998

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• A. Springer, A. Pohl, W. Gugler, M. Huemer, L.M. Reindl, C. C. W. Ruppel, F. Seifert, R. Weigel
  A robust ultra broadband wireless communication system using SAW chirped delay lines
  1998 Proc. 1998 IEEE MTT-S International Microwave Symp., ISBN: 0-7803-4472-3, ISSN 0149-645X, pages: 491 - 494
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  Abstract

  Design and performance of SAW chirped delay lines on LiTa03-Xl 12rotY for a wireless communication system are presented. Center frequency bandwidth and chirp rate are 350 MHz, 80 MHz, and +20 MHz/s, respectively. An optimized square-root weighting was chosen to reduce the sidelobes of the compressed pulse to –42 dB compared to the correlation peak. The chirp filters have been deployed in a hardware demonstrator for a wireless indoor communication system for data rates of a few MBit/s. Limiting factors for the data rate according to simulations and measurements are mainly the intersymbol interference due to the time-overlapping of consecutive symbols and to a lower extent the multipath propagation.
• L.M. Reindl, C. Ruppel, K. Riek, T. Pankratz, R. Weigel
  A wireless AQP pressure sensor using chirped delay line structures
  1998 Proc. 1998 IEEE Ultrasonics Symp., pages: 355 - 358
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  Abstract

  We report of the design of a SAW delay line developed for a wireless pressure sensing system operating in the 434 MHz ISM-band. The structure is an one port configuration fabricated on quartz 37.5°rotYX. It is hermetically sealed in all-quartzpackage (APQ) technology with the SAW structure being placed on a diaphragm inside the cavity. The sensor allows for the measurement of absolute pressure values in the range from 0 to 8.5 bar. The SAW structure shows a linear phase although it incorporates chirped SAW components for enhancing the sensor sensitivity. The SAW structure is built up of two overlap-weighted dispersive split finger interdigital transducers (IDTs). An improvement of the sensor sensitivity by a factor of 32 compared to systems using non-dispersive SAW components has been achieved.
• L.M. Reindl, G. Scholl, T. Ostertag, C. Seisenberger, J. Hornsteiner, A. Pohl
  Berührungslose Messung der Temperatur mit passiven OFW Sensoren
  1998 Tagungsband VDI/GMA Temperatur 98, volume: 1379, pages: 93 - 98
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  Abstract

  Surface acoustic wave (SAW) radio transponders make it possible to read measurement values from remote. The passive SAW transponder store the interrogation signals until all environmental echoes are vanished. The answer signal of the sensor is coded according to the temperature at the sensor location. In this paper we discuss the principles of wireless passive SAW transponders. Examples for measuring the temperature of a break disc and of a rotor of a electric motor are presented.
• A. Pohl, L.M. Reindl, F. Seifert, R. Weigel
  Chirp gating enhances performance of chirp spread spectrum systems
  1998 München, Germany Proc. IEEE 1998 MTT/AP International Workshop on Commercial Radio Sensor and Communication Techniques, pages: 32 - 37
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  Abstract

  The application of chirp spread spectrum systems for a reliable indoor communication system operated in the 2.45 GHz ISM band is shown. A test system have been built applying surface acoustic wave dispersive delay lines (SAW chirp filters) for chirp impulse compression. Gating of a chirp signal and the according compressive device means gating in time and frequency domain simultaneously. If only a part of the chirp is transmitted or received, the impulse compression still delivers useful output signals. This fact can be utilized for transmission of additional data information in chirp gaps with gap position modulation and for leaving out a sub band during transmission, to avoid jamming of other narrowband communication systems operating in this frequency band. It also can be applied for our new method of adaptive interference suppression introduced here. With a tapped dispersive SAW delay line the frequency band for chirp transmission is divided into a number of intervals. If one or some of these sections are occupied, they can be spared out in the transmitter or if a narrowband jammer is received within such subbands, they can be gated and disregarded for the impulse compression. This yields a technique for fast adaptive jamming cancellation without a loss of the simplicity of a SAW based Spread Spectrum system. The experimental system was tested in different electromagnetically polluted indoor areas. Simulations and some preliminary experimental results are presented.
• F. Seifert, A. Pohl, L.M. Reindl, R. Steindl
  Drahtlose Abfrage von Oberflächenwellen- Identifikationsmarken und Meßwertwandlern
  1998 E&I, volume: 115, issue: 7/8, pages: 360 - 370
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  Abstract

  Wireless readout of surface acoustic wave identification tags and sensors. We describe wireless readout of 3 different species of passive surface acoustic wave (SAW) identification tags and sensors which are all connected to a small antenna for reception of the interrogation signal and transmission of the delayed sensor response. (1) Following the ringing out of SAW resonators using a phase locked loop (PLL) over several microseconds, their resonance-("Eigen"-)frequencies are determined. (2) The time between some response impulses in a SAW delay line, caused by acoustical reflectors in different distances, accurately is measured by 3 different signal integrating methods. (3) Amplitude variations of the response impulse, due to variations of a capacitance externally connected to the SAW delay line are evaluated. All methods are used for wireless readout of fixed and adjustable identification codes and sensor measurands e.g. temperature, pressure, mechanical force, torque, deformation, electrical voltage etc.
• A. Springer, M. Huemer, W. Gugler, R. Weigel, L.M. Reindl, C. C. W. Ruppel, A. Pohl, F. Seifert
  Ein OFW-basiertes Übertragungsverfahren für Anwendungen in drahtlosen lokalen Netzen
  1998 Oberpfaffenhofen, Deutschland Proceedings ITG Fachtagung Wellenausbreitung bei Funksystemen und Mikrowellensystemen, pages: 85 - 93
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  Abstract

  In diesem Beitrag wird ein kostengünstiges Funkkommunikationssystem speziell für Innenräume und industrielle Einsatzgebiete vorgestellt. Um eine störsichere Übertragung zu realisieren verwendet das System Chirp-Signale. Die Generierung der Chirp-Signale sowie deren signalangepaÿte Filterung erfolgt mit OFWFiltern auf LiTaO3. Die Filter erzeugen Chirp- Signale mit einer Bandbreite von 80 MHz, einer Mittenfrequenz von 348.8 MHz und einer Chirp-Rate von +/-40 MHz/µs. Zur Reduktion der Nebenzipfel der komprimierten Impulse im Empfänger auf -42 dB gegenüber dem Korrelationsmaximum wurde die Gewichtung der Übertragungsfunktion optimiert. Die Funktionsweise des Systems bis zu einer Datenrate von 5 MBit/s wurde mit einem Testaufbau demonstriert. Wie Simulation und Messung ergaben, wird die Datenrate hauptsächlich durch Intersymbolinterferenz und nur in geringem Maße durch die Mehrwegeausbreitung begrenzt.
• A. Pohl, G. Ostermayer, L.M. Reindl, F. Seifert, R. Weigel
  Fast adaptive interference cancellation in low cost SAW based chirp spread spectrum systems
  1998 Proc. 1998 IEEE International Symposium on Spread Spectrum Techniques & Applications (ISSSTA), ISBN 0-7803-4281-X, pages: 883 - 887
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  Abstract

  For a fast reliable data transmission in a heavily distorted indoor environment, a SAW based chirp spread spectrum system operating in the 2.45 GHz ISM is presented. Due to the implementation of SAW matched filters for impulse compression, the system design remains low cost. The use of a bandwidth as wide as allowed make it possible to overcome Rayleigh fading with large coherence bandwidths. A matched filter system is susceptible for jammers, passing the matched filter like a bandpass. Therefore a technique of fast adaptive cancellation without a loss of simplicity is presented. The system was tested in different electromagnetically polluted indoor areas. Some preliminary experimental results are presented.
• L.M. Reindl, G. Scholl, T. Ostertag, F. Schmidt, A. Pohl
  Funksensorik und Identifikation mit OFW Sensoren
  1998 Sensortagung Bad Nauheim, Germany ITG/GMA Fachbericht 148 Sensoren und Meßtechnik, ISBN 3-8007-2330- 1, VDE Verlag, pages: 77 - 86
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  Abstract

  Durch Oberflächenwellen (OFW)-Bauelemente werden neuartige Identifikations- und Sensorelemente (Transponder) ermöglicht, die funkauslesbar und passiv sind. Die Transponder speichern die Abfragesignale, bis alle Umgebungsechos abgeklungen sind. Dann wird ein charakteristisches Antwortmuster des Transponders zum Abfragegerät zurückgestrahlt. Identmarken antworten dabei mit ihrem konstanten Identifikationsmuster. Im Falle der Funksensoren wirkt die physikalische oder chemische Meßgröße auf die Ausbreitungseigenschaften der OFW ein und verändert so das Antwortmuster. In dem Beitrag wird das Funktionsprinzip dieser Transponder erläutert. Als Anwendungsbeispiele werden Identmarken für Bahnanwendungen, die Messung der Temperatur auf einer Bremsscheibe und auf einem Läufer eines Elektromotors gezeigt, die Messung des Reifendrucks während der Fahrt und ein Stromsensor gezeigt.
• A. Pohl, M. Brandl, R. Steindl, L.M. Reindl, F. Seifert
  Gated chirps for signal processing and communication engineering
  1998 Proc. 1998 IEEE Ultrasonics Symp., pages: 359 - 362
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  Abstract

  A method of signal processing in SAW based chirp impulse compression systems, yielding a better performance and an enhanced capability of interference suppression is introduced. Therefore, the interdigital transducers' bus bars of the dispersive delay line are interrupted, each tap is connected to a pin of the package. The coherent summation is done outside of the device. Frequency and time domain are linked due to the chirp dispersion, the time domain instantaneously is coupled to the geometry of the SAW device due to the propagating acoustic wave. Therefore, gating away of one or more taps represents switching off the chirp in time and frequency domain, respectively. The method can be applied for a wide range of applications, for interference reduction, control of the transmitted spectrum, etc. Due to its simplicity it is suitable even for low cost systems. Theoretical and experimental results prove the capability of the method.
• T. Pankratz, H. Scherr, L.M. Reindl, C. Ruppel, R. Weigel
  Low TB radio SAW sensors incorporating chirped transducers and reflectors for wireless pressure sensing applications
  1998 Proc. 1998 IEEE MTT-S International Microwave Symp., ISBN: 0-7803-4472-3, ISSN 0149-645X, pages: 845 - 848
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  Abstract

  We report on the design and performance of two basic SAW delay line structures developed for a wireless pressure sensing system operating at 434 MHz. The pressure sensor has been fabricated in all-quartz-package (AQP) technology with the SAW structures being placed on a diaphragm inside the hermetically sealed cavity. Both SAW structures show a linear phase although they both incorporate chirped SAW components for enhancing the sensor sensitivity. They have low time-bandwidth (TB) products of 2 and 11, respectively. We attained an improvement of the sensor sensitivity by factors of up to 20 compared to sensors employing non-dispersive SAW components.
• A. Pohl, L.M. Reindl
  Measurement of physical parameters of car tires using passive SAW sensors
  1998 AMAA (Advanced Microsystems forAutomotive Applications), 1998 ISBN 3-540-64091-6, Springer Berlin Heidelberg New York, pages: 250 - 262
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  Abstract

  A new type of sensors based on surface acoustic wave devices are introduced. The sensor elements are totally passive and are only connected to an antenna. The readout is performed wirelessly via a radio link. The sensors are characterized by high thermal, mechanical and electromagnetic loadability and nearly unlimited lifetime. Affecting the sensors with the measurand a lot of physical parameters can be measured without wired connection. The application of these new elements for measurements in cars focused to the tires are discussed. The hardware required and examples for application in automotive industry are presented.
• A. Pohl, A. Springer, L.M. Reindl, F. Seifert, R. Weigel
  New applications of wirelessly interrogable SAW sensors
  1998 Proc. 1998 IEEE MTT-S International Microwave Symp., ISBN: 0-7803-4472-3, ISSN 0149-645X, pages: 503 - 506
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  Abstract

  Applying passive wirelessly interrogable SAW sensors a lot of physical parameters can be measured. Up to now all SAW sensor applications are performed by taking a snapshot of the sensor's response periodically, evaluating the measurand assumed to be quasistationary. Therefore the upper limit for rate of sampling a mechanical affect to the sensor is the interrogation rate. Usually it is in the range of 100 kHz or less, measurands with a periodicity of up to a few tenths of kHz can be sampled satisfactory. Even audible vibrations of machine parts can be monitored. Here, the behaviour of the sensors for dynamic measurands is discussed. Advanced applications for the measurement of vibration, acceleration, for dynamic pressure measurement in mechanical engineering, for example for monitoring the tires of cars are presented. Measurement results from an experimental setup are given.
• R. Steindl, A. Pohl, L.M. Reindl, F. Seifert
  SAW delay lines for wirelessly requestable conventional sensors
  1998 Proc. 1998 IEEE Ultrasonics Symp., pages: 351 - 354
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  Abstract

  Programmable reflectors of SAW ID-tags can be employed as passive transponder for conventional sensors of the capacitive, inductive and resistive type. The programmable reflector is a loadable split finger transducer, other fixed reflectors are used as reference bits. An noncoherent read out signal processing is sufficient, because the load of the programmable reflector influences both, the phase and amplitude of the reflected wave. The principle is discussed, setup and results of some actual measurements are presented.
• W. Gugler, M. Huemer, A. Springer, A. Pohl, L.M. Reindl, R. Weigel, F. Seifert
  Simulation and verification of a spread spectrum wireless LAN using SAW chirped delay lines
  1998 Proc. 1998 IEEE International Symposium on Spread Spectrum Techniques & Applications (ISSSTA), ISBN 0-7803-4281-X, pages: 898 - 901
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  Abstract

  We present a wireless spread spectrum system based on SAW chirped delay lines on LiTaO3-X112rotY operating in the ISM band at 2.45 GHz. Center frequency, transmission bandwidth, chirp rate, and data rate are 348.8 MHz, 80 MHz, ±40 MHz/µs, and 2 Mbits/s, respectively. Due to the reduction of the sidelobes of the compressed pulse to -42 dB, a high processing gain of 22 dB, and the large transmission bandwidth our system is robust against narrrowband fading and noise. This paper describes the design, technology and measurement results of the used SAW chirped delay lines. The proposed communication system and simulation results are presented, measurements obtained with a hardware demonstrator are given, and the limiting factors of the data rate of our system are shown.
• W.-E. Bulst, G. Fischerauer, L.M. Reindl
  State of the art in wireless sensing with surface acoustic waves
  1998 Proceedings of the 24th Annual Conference of the IEEE Industrial Electronics Society IECON 98, ISBN 0-8194-2459-5, pages: 2391 - 2396
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  Abstract

  Surface acoustic wave (SAW) devices can be turned into novel identification and sensor elements (transponders) that do not need any power supply and may be interrogated wirelessly. Such a transponder picks up an electromagnetic request signal and stores it until all echoes caused by multi-path propagation have died away. Then, a characteristic response signal is beamed back to the interrogator unit. In radio-link sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. – This contribution surveys the operating principle of such sensors and their state-of-the-art performance. The discussion is supported by illustrative examples such as temperature sensors and sensors for mechatronic applications.
• R. Weigel, L.M. Reindl
  Wireless SAW sensor techniques
  1998 Tokio, Japan Proc. Meeting on New High Performance Piezoelectric Single Crystals and Thin Films, and Applications for Next Generation Electronics and Communication Systems, pages: 21 - 26
• G. Scholl, F. Schmidt, T. Ostertag, L.M. Reindl, H. Scherr, U. Wolff
  Wireless passive SAW sensor systems for industrial and domestic applications
  1998 Proc. 1998 IEEE Frequency Control Symp., pages: 595 - 601
• L.M. Reindl, G. Scholl, T. Ostertag, A. Pohl, R. Weigel
  Wireless remote identification and sensing with SAW devices
  1998 München, Germany IEEE 1998 MMT/AP International Workshop on Commercial Radio Sensor and Communication Techniques, pages: 83 - 96
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  Abstract

  Surface acoustic wave (SAW) devices can be used as novel identification and sensor elements (transponders) that do not need any power supply and may be requested wirelessly. Such a transponder picks up an electromagnetic request signal and stores it until all echoes caused by multi-path propagation have died away. Then, a characteristic response signal is returned to the interrogator unit. Identification marks respond with their nonchanging identification pattern. In radio-link sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. This paper surveys the operating principle of such sensors and their state-of-the-art performance. The discussion is illustrated by several examples such as temperature sensors and sensors for mechatronic applications.
• A. Pohl, R. Steindl, L.M. Reindl, F. Seifert
  Wirelessly interrogable sensors for different purposes in industrial radio channel
  1998 Proc. 1998 IEEE Ultrasonics Symp., pages: 347 - 350
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  Abstract

  The radio request of passive wirelessly interrogable surface acoustic wave sensors is discussed. The parameters of the measurement process are divided to the contributions of the sensor, the radio channel and the radio request method. The measurement bandwidth and an example for an actual radio channel are discussed. For matching of the method to the measurement problem, the parameters of different radio request methods are estimated.

1997

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• A. Zenzinger, F. Morhart, L.M. Reindl, R. Weigel
  A SAW shaping filter for high data rate MSK-encoding in a broadband DS-CDMA system
  1997 Proc. 1997 IEEE MTT-S International Topical Symposium on Technologies for Wireless Applications, ISBN: 0-7803-3318-7, pages: 135 - 138
• L.M. Reindl, U. Rösler, C. Ruppel, R. Obertreis, R. Weigel
  Chirped SAW devices for wireless passive sensors
  1997 Proc. 1997 IEEE Ultrasonics Symp., ISSN: 1051-0117, page: 343
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  Abstract

  Chirped structures as sensing elements in a delay line allow for the variation of the sensitivity over a wide range. A sensor system operating at a center frequency of 434 MHz and a system bandwidth of 1.7 MHz will be shown. We designed dispersive inline SAW structures with two chirped and apodized IDTs. Two expanders, one with an up- and the other with a down-chirp, have been built on quartz 37.50 cut. The corresponding compressors (down- and up-chirp) are the sensor elements and have a wider bandwidth to compensate for the frequency shift due to the sensor effect. The compressors have been built on quartz for mechanical sensing and on LiNbO3, YZ-cut for temperature sensing. To avoid bulk wave conversion we used a modulated IDT with 8 electrodes per electrical period. On quartz we operated these IDTs on the 3rd and on LiNbO3 on the 5th harmonic which is lower than the onset frequency for bulk wave conversion and gives a suitable impedance level as well. We present theoretical and experimental results for the devices and show results of the corresponding sensor systems for temperature.
• L.M. Reindl, F. Kalabic, G. Ostermayer, A. Pohl, F. Seifert, R. Weigel
  Design of a SAW expander and compressor on LiTaO3 for a TCDMA spread spectrum system
  1997 Proc. 1997 IEEE International Microwave Symp. , ISBN: 0-7803-3814-6 / ISSN: 0149-645X, pages: 821 - 824
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  Abstract

  Abstract—We report on the design and performance of surfaceacoustic wave (SAW) minimum shift keying (MSK) tapped delay lines using pseudonoise code sequences with a length of 128 chips. As a substrate, X112°rotY-LiTaO3 has been used due to the system requirements of a given CDMA/TDMA (TCDMA) radio communication system. System IF frequency, bandwidth of the major lobe, and integration time of the SAWdevices were, respectively, 360 MHz, 63.5 MHz, and 3 µs. We used SAW tapped delay lines employing nonweighted as well as cosine-weighted input interdigital transducers incorporating split-fingers. We designed both expander as well as compressor filters attaining very similar experimental results. We found insertion loss values down to 16 dB and amplitude ripples of less than 2 dB. The close-in selectivity was 28 dB.
• L.M. Reindl, H. Scherr, A. Pohl
  Drahtloses Messen mit passiven OFW Sensoren am Beispiel der Überwachung des Reifenluftdruckes
  1997 Hannover, Germany 6. VDI Fachtagung Reifen, Fahrwerk, Fahrbahn
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  Abstract

  Fundamentals of surface acoustic wave (SAW) sensors and their implementation for measurement of tire pressure during driving are shown. SAW sensors are passive devices, they are free of maintenance. The lifetime of the sensors is not limited, it is much more than the lifetime of every known battery and semiconductor technology. The sensors withstand rough environment characterized by heat, dirt, mechanical vibration and/or electromagnetic interference. Results of the tire pressure measurements during test rides are presented.
• A. Zenzinger, S. Mathiae, P. Russer, L.M. Reindl, R. Weigel
  MSK direct sequence spread spectrum system incorporating SAW tapped delay lines and SAW shaping filter
  1997 Proc. 1997 IEEE Ultrasonics Symp., ISSN: 1051-0117, pages: 313 - 316
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  Abstract

  The present work deals with the IF section of an indoor wireless TDMA/CDMA (TCDMA) communication system operating in the 2.45 GHz ISM band [1, 2]. Spreading and despreading is done at the 361 MHz IF with an extremely wide bandwidth of 65 MHz which is greater than the coherence bandwidth of the UHF indoor radio channel. For the modulation of the data we employ on off keying (OOK), and for the spreading minimum shift keying (MSK). Two types of MSK modulators have been devel- oped, one with a SAW tapped delay line (TDL) and one with a SAW shaping filter. Despreading is done by another SAW TDL, which operates as a matched filter.
• A. Pohl, G. Ostermayer, L.M. Reindl, F. Seifert
  Monitoring the tire pressure at cars using passive SAW sensors
  1997 Proc. 1997 IEEE Ultrasonics Symp., pages: 471 - 474
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  Abstract

  In our paper we present the application of surface acoustic wave (SAW) sensors to the continuous monitoring of the tire pressure in road vehicles. With these, the tire pressure can be read out in every phase of driving. We show the implemented prototype setup for measurement of the tire pressure, the applied SAW sensors, improved versions and the interrogation setup. The problems in practical application are discussed. Experimental results measuring the tire pressure during test rides are presented.
• G. Ostermayer, A. Pohl, L.M. Reindl, F. Seifert
  Multiple access to SAW sensors using correlative signal processing
  1997 Proceedings SENSOR ´97, volume: 1, pages: 241 - 246
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  Abstract

  In this paper we present a method of solving the problem of access to more than one passive surface acoustic wave (SAW) sensor in the range of a single interrogation system. The sensor informations of the SAW sensors are evaluated almost simultaneously by use of the correlation property of BPSK-coded sensors. In general a SAW sensor is affected by a measurement quantity in two ways: a change of the length of the substrate and a change of the propagation velocity of the SAW. Both influences yield a time scaling of the sensor's impulse response. If the interrogation signal is exactly the time-inverse of the sensor's impulse response the sensor will answer with its autocorrelation function (ACF). By changing the time scaling factor Sint of the interrogation signal one gets different correlation functions with of course different peaks. The highest peak will appear if the scaling factors of the sensor impulse response and the interrogation signal are identically. This matching scaling factor Sm provides evaluatin the measurement quantity. All the used sensors have the same code but different time delays. So the received signal is a succession of correlation peaks due to the different sensors. By time windowing one is able to evaluate the information of each sensor almost simultaneously. We show the principal concept, mathematical simulations, numerical estimations and finally an overview of the design of such a SAW sensor system.
• G. Ostermayer, A. Pohl, L.M. Reindl, F. Seifert
  Multiple access to SAW sensors using matched filter properties
  1997 Proc. 1997 IEEE Ultrasonics Symp., pages: 339 - 342
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  Abstract

  In this paper we present a method of solving the problem of access to more than one passive surface acoustic wave (SAW) sensor in the range of a single interrogation system. The sensor informations of the SAW sensors are evaluated almost simultaneously by use of the correlation property of BPSK-coded sensors. We show the principal concept, mathematical simulations, numerical estimations and finally an overview of the design of such a SAW sensor system.
• A.P. Mayer, E.A. Mayer(Garova), V.G. Mozhaev
  Nonlinear surface and wedge acoustic waves in the presence of weak dispersion
  1997 Proc. Estonian Acad. Sci. Phys. Math., volume: 46, pages: 85 - 93
• A. Pohl, G. Ostermayer, L.M. Reindl, F. Seifert
  Notch sensors - a new signal processing method for interrogation of passive SAW sensors
  1997 Proc. 1997 IEEE Ultrasonics Symp., pages: 355 - 358
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  Abstract

  A new signal processing method for wireless interrogation of a passive SAW sensor with multiple reflectors, utilizing the signal interference during overlap of the sensor's response bursts is introduced. Within this time interval, the amplitude or the phase, respectively, is measured. By varying the frequency of the relatively long interrogation bursts, destructive interferences (notches) are searched. So the measurand influencing the sensor or its identification information can be gained. The principle yields high resolution using a low cost interrogating system. The principle, the hardware effort and experimental results for temperature measurements are presented.
• R. Weigel, L.M. Reindl, F. Seifert
  SAW programmable and fixed-code matched filters for CDMA mobile radio applications
  1997 Proc. 1997 Progress in Electromagnetics Research Symposium (PIERS), ISBN: 962-442-097-1, page: 443
• L.M. Reindl
  Track-changing structures on YZ-LiNbO3
  1997 Proc. 1997 IEEE Ultrasonics Symp., pages: 77 - 82
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  Abstract

  Several types of track changers on YZLiNbO3, operating at 434 MHz, have been compared: Conventional 3 dB multistrip couplers (MSC) combined with reflecting multistrip couplers (RMSC) and group type track changers with 3 and 4 electrodes per wave length, respectively. In order to determine the 4-port S-matrix of these track changers experimentally, a test structure consisting of 4 IDTs has been developed and fabricated. We will present theoretical and experimental results of track changers with different acoustic apertures and numbers of electrodes.
• A. Pohl, G. Ostermayer, L.M. Reindl, F. Seifert
  Wireless measurement of tyre pressure using SAW passive sensors
  1997 Proceedings SENSOR ´97, volume: 1, pages: 89 - 94
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  Abstract

  A new type of passive surface acoustic wave (SAW) -sensors for wireless readout and their application to the measurement of the air pressure in the tires of road vehicles in motion is presented. With this, the tire pressure can be read out in every phase of driving. With the implemented system, a resolution of better than 0.05 Bar is achieved. The sensors are passive devices and are absolute maintenance free. The lifetime of the sensors is not limited, it is much more than the lifetime of every known battery technology. The sensors withstand rough environment characterized by heat, dirt, mechanical vibration and/or electromagnetic interference. We show the implemented prototype setup for measurement of the tire pressure, the applied SAW sensors, an improved version and the interrogation setup. The problems in practical application are discussed. Results of measurements of the tire pressure during test rides are presented.
• L.M. Reindl, G. Scholl, T. Ostertag, C.C.W. Ruppel, W.-E. Bulst, F. Seifert
  Wireless remote identification and sensing with SAW devices
  1997 Proceedings SENSOR ´97, volume: 1, pages: 161 - 166
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  Abstract

  Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation with no need for a separate power supply, and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond on an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. In this paper we discusse the principles of wireless passive SAW transponders. Examples for several applications will be presented.

1996

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• A. Zenzinger, F. Morhard, L.M. Reindl, R. Weigel
  A SAW shaping filter for high data rate MSK-encoding in a broadband DS-CDMA system
  1996 IEEE MTT-S International Topical Symposium on Technilogies for Wireless Applications, pages: 135 - 138
• G. Ostermayer, A. Pohl, C. Hausletner, L.M. Reindl, F. Seifert
  CDMA for wireless SAW sensor applications
  1996 Proc. 1996 IEEE Symposium on Spread Spectrum Techniques & Applications (ISSSTA), pages: 795 - 799
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  Abstract

  A well known spread spectrum technique is used to get the sensor information from an individually addressed SAW sensor. Coded ID tag type and BPSK type SAW sensors are picked out of a number of sensors by correlating the received signal with the known code of a particular sensor. The ID-tag type and BPSK-coded SAW sensor´s function is observed as a scaling of time and shape respectively. The time scaling factor is equal to the mechanical extension of the substrate of a sensor due to temperature, etc. This scaling factor is evaluated by use of correlative signal processing techniques. The principal concept, mathematical simulations, numerical estimations and finally an overview of the implemented SAW sensor system are shown. Preliminary results for readout of OOK and BPSK coded passive remote SAW sensors using the Wavelet Transform processed within a SAW convolver are presented.
• C.C.W. Ruppel, L.M. Reindl, S. Berek, U. Knauer, P. Heide, M. Vossiek
  Design, fabrication and application of precise delay lines at 2.45 GHz
  1996 Proc. 1996 IEEE Ultrasonics Symp., pages: 261 - 265
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  Abstract

  For years linear optimization algorithms have been used successfully in bandpass filter design. This method has been adopted for the design of dispersive interdigital transducers (IDTs) for pulse compression filters with low time-bandwidth products, and for the design of delay lines with linear phase. Now this method has been extended to the design of dispersive IDTs operating at higher harmonics. As examples, delay lines at 2.45 GHz operating at the fundamental and third harmonic with relative bandwidths up to 30 % will be presented. The delay lines operating at the fundamental harmonics were fabricated on the rotated cut of LiNbO3 and had normal fingers only. The relative height of the metallization was chosen for minimum reflections. Minimum linewidth of 0.3 μm were necessary. The delay lines operating at the third harmonic had split fingers for canceling reflections. Therefore minimum linewidths of approximately 0.45 μm had to be realized. Measured and calculated frequency responses of these delay lines will be compared with each other. Taking advantage of the reported delay lines, a novel FMCW radar system incorporating a 2.45 GHz SAW reference path is established. The proposed SAW based system achieves a higher dynamic range than the conventional FMCW radar sensors.
• A. Pohl, C. Posch, L.M. Reindl, F. Seifert
  Digitally controlled compressive receiver
  1996 Proc. 1996 IEEE Symposium on Spread Spectrum Techniques & Applications (ISSSTA), pages: 409 - 413
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  Abstract

  An adaptive compressive receiver with electronically controlled parameter adjustment for applications like spectrum monitoring of frequency hopped spread spectrum signals is presented. For fast realtime signalprocessing with high time-bandwidth product a SAW convolver is used. We achieve a resolution of 125 kHz over 80 MHz bandwidth. The presented system employs some new digital concepts for the generation of the rf signals and signal windowing and weighting usable to comprehensive use of the high performance convolver. The system shows satisfactory performance and applicability in a wide range of realtime signal analysis.
• G. Schromm, W. Pietsch, F. Seifert, L.M. Reindl
  Real-time measurement of the Wigner distribution with a SAW convolver
  1996 Proc. 1996 IEEE IMTC, volume: 2, pages: 891 - 894
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  Abstract

  A new method for measuring the Wigner distribution (WD) of a signal is presented. Using a surface acoustic wave convolver as fast computing element and an oscilloscope as display element a unique way of computing the WD of a signal (e.g., the impulse response of a linear system) has been investigated. An experimental system has been built and used to measure the WD of several different filters and signals. The mathematical background of the method, its limitations and dependence on the properties of the convolver, and possible implementations are investigated.
• G. Schromm, W. Pietsch, L.M. Reindl, F. Seifert
  Real-time signal analysis with the Wigner distribution using a SAW convolver
  1996 IEEE Symposium on Spread Spectrum Techniques & Applications Proc., pages: 801 - 803
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  Abstract

  A new method for determining the Wignerdistribution (WD) of broadband signals is presented. Using a surface acoustic wave convolver as fast computing element and an oscilloscope as display element a unique way of computing the WD of a signal (e.g., the impulse response of a linear system) has been investigated. An experimental system has been built and used to measure the WD of several different filters and signals. The mathematical background of the method, its limitations and dependence on the properties of the convolver, and possible implementations are investigated.
• L.M. Reindl, G. Scholl, T. Ostertag, C.C.W. Ruppel, W.-E. Bulst, F. Seifert
  SAW devices as wireless passive sensors
  1996 IEEE Ultrasonics Symp., pages: 363 - 367
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  Abstract

  Surface acoustic wave (SAW) radio sensors make it possible to read measurement values from a remote location. The decisive advantage of these SAW sensors lies in their passive operation with no need for a separate power supply, and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW sensors are maintenance free. The physical or chemical properties that shall be detected change the propagation characteristics of the SAW. In this paper we compare the sensitivity of different types of SAW sensors. These are resonators, reflective delay lines, and dispersive structures. Examples for several applications will be presented.
• C.C.W. Ruppel, L.M. Reindl
  SAW devices for spread spectrum applications
  1996 Proc. 1996 IEEE Symposium on Spread Spectrum Techniques & Applications (ISSSTA), (INVITED PAPER), pages: 713 - 719
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  Abstract

  Surface acoustic wave (SAW) filters are small, rugged, and crystal stable. They can be fabricated with high reproducibility. In the 80's they replaced the LC filters in TV sets and more than one hundred million SAW TV IF filters are fabricated each year. SAW filters play a key role in the rapidly growing market of mobile communication systems. They enable advanced system concepts and contribute to the reduction of the size of the handhelds. They are used in the IF and RF stage as well. SAW filters are also used for channel filtering in narrowband code division multiple access (CDMA) mobile communication systems. A new application for SAW filters might be as analog correlators in broadband CDMA communication systems. Compared to digital signal processors (DSP) they exhibit a relative low power consumption and can perform real-time correlation of signals with absolute bandwidths up to a few hundred MHz easily. One drawback is the limitation of the integration time length of SAW devices, which is typically less than 16 μs due to the size of the substrate wafers (typically 3"). Requirements on SAW devices as analog correlators are stringent with respect to insertion loss, stopband attenuation, amplitude ripple and phase nonlinearity. To fulfill these requirements efficient CAD tools for the simulation and synthesis of SAW devices are a prerequisite.
• R. Weigel, C. Knorr, F. Kalabic, F. Seifert, K. Wagner, L.M. Reindl
  SAW fixed-code matched filters for wireless spread spectrum consumer communications
  1996 Proc. 1996 26th European Microwave Conference (ISBN: 1-8999-1908-2), pages: 763 - 767
• A. Pohl, G. Ostermayer, L.M. Reindl, F. Seifert
  Spread spectrum techniques for wireless interrogable passive SAW sensors
  1996 Proc. 1996 IEEE Symposium on Spread Spectrum Techniques & Applications (ISSSTA), pages: 730 - 734
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  Abstract

  Recently surface acoustic wave (SAW) sensors for temperature, pressure, strain, etc. were investigated and tested. They use the change in SAW time delay due to the quantity to be measured. Increasing interest was initiated by the possibility of wireless readout. It is shown here, that the well known spread spectrum techniques (chirp impulse compression, CDMA, etc.) allows an increase of both, sensitivity and accuracy of measurement and a discrimination of several sensors simultaneously interrogated. Some applications (temperature measurement with mK resolution, coded sensors) are demonstrated. We show some mathematical simulations and preliminary experimental results.

1995

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• L.M. Reindl, V. Magori
  Funksensorik mit passiven Oberflächenwellen-Komponenten (OFW)
  1995 VDI, Reihe8: Meß-, Steuerungs- und Regeltechnik, volume: 515, pages: 62 - 79
• R. Weigel, C. Knorr, L.M. Reindl, K.C. Wagner, F. Seifert
  MSK SAW tapped delay lines on LiTaO3 with moderate processing gain for CDMA indoor and mobile radio applications
  1995 Proc. IEEE Ultrasonics Symp., pages: 167 - 170
• G. Schromm, W. Pietsch, F. Seifert, L.M. Reindl, Ch. Arabjan
  Real-time Wigner distribution with a SAW-convolver
  1995 Proc. IEEE Ultrasonics Symp., pages: 137 - 142
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  Abstract

  A new method for determining the Wignerdistribution (WD) of broadband signals is presented. Using a surface acoustic wave convolver as fast computing element and an oscilloscope as display element a unique way of computing the WD of a signal (e.g., the impulse response of a linear system) has been investigated. An experimental system has been built and used to measure the WD of several different filters and signals. The mathematical background of the method, its limitations and dependence on the properties of the convolver, and possible implementations are investigated.
• F. Schmidt, O. Sczesny, L.M. Reindl, V. Magori
  Versatile systems for remote SAW sensor applications
  1995 Nürnberg SENSOR'95, pages: 539 - 543
• A. Pohl, T. Ostermayer, F. Seifert, C. Hausleitner, L.M. Reindl
  Wavelet transform with SAW-convolver for sensor application
  1995 Proc. IEEE Ultrasonics Symp., pages: 143 - 146
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  Abstract

  To get the sensor information from an individually adressed SAW sensor, the use of coded ID-tag type SAW sensors is combined with the tool of Wavelet transform, a kind of correlative signal processing. The function of SAW sensors (ID-tag type) is observed as a scaling of time and shape respectively. The time scaling factor is equal to the mechanical extension of the substrate of a sensor for temperature, etc. This scaling factor is evaluated by calculating the Wavelet transform. The fundamental concept, mathematical simulations, numerical estimations and finally an overview of the implemented SAW sensor system using the Wavelet transform processed within a SAW convolver are shown. Preliminary results are presented.
• A. Pohl, C. Posch, F. Seifert, L.M. Reindl
  Wideband compressive receiver with SAW-convolver
  1995 Proc. IEEE Ultrasonics Symp., pages: 155 - 158

1994

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• L.M. Reindl, T. Ostertag, W. Ruile, C.C.W. Ruppel, A. Lauper, R. Bächtiger, H. Ernst
  Hybrid SAW-device for a European train control system
  1994 Proc. IEEE Ultrasonics Symp., pages: 175 - 179
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  Abstract

  The use of surface acoustic wave devices for a European train control system (ETCS) as stationary transponder is shown. The Surface Acoustic Wave (SAW)-Device in such a system acts as a local coherent oscillator for the balise. We show the design and analysis of the dynamically programmable SAW delay line. We use one single phase unidirectional transducer (SPUDT) for coupling the electromagnetic wave received by an antenna to the acoustic wave and vice versa. (For the test system we built a tag with 8 switchable reflectors and one additional fixed reflector as reference bit.) The switchable reflectors are designed as split finger transducers which are connected via bond wires to a hybrid circuitry. This circuitry consists of capacitors and inductors for matching, and GaAs-FETs for switching. Measurements with this programmable hybrid SAW-Delay line show dynamic range of 25 dB between "ON" and "OFF" reflectors with good reproducibility.
• R. Weigel, A. Fauter, P. Russer, L.M. Reindl, F. Seifert
  On the design of moderate time-bandwidth SAW convolver for indoor and mobile radio applications
  1994 PIMRC Proceedings of Wireless Networks Catching the mobile future, volume: 1, pages: 379 - 383
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  Abstract

  Up to now, the main applications of surface acoustic wave (SAW) convolvers have been military and have required high processing gain values. Rather complex hybrid fabrication technologies have to be employed needing large packages and resulting in expensive devices. Recent applications in radio frequency (RF) consumer communications use relatively short code sequences. For these systems, low-cost SAW convolvers with moderate time-bandwidth products in the order of a few hundred have many interesting features. To meet the demands for low price and high reliability, precise reproducible designs and economic mass production of the devices are indispensible. We report on the design and performance of a small and compact prototype SAW convolver. Input center frequency, integration time and time-bandwidth product are 350 MHz, 3 ps and 150, respectively.
• C.C.W. Ruppel, L.M. Reindl, K.C. Wagner
  Optimum design for low time-bandwidth product SAW filters
  1994 Proc. IEEE Ultrasonics Symp., pages: 61 - 65
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  Abstract

  For years linear optimization algorithms have been used successfully in bandpass filter design. This method has been adopted for the design of pulse compression filters with low time-bandwidth products. In the bandpass filter design, the sidelobe level in the frequency domain is optimized for a fixed impulse response length. In case of the design of a low timebandwidth product filters, we optimize the sidelobe suppression in the time domain for a fixed overall bandwidth. We get the optimum time response for a given frequency bandwidth and width of the compressed pulse. The spurious time response is minimized. The corresponding optimum frequency response is split up onto expander and compressor, each consisting of two chirped and apodized IDTs. As an example, an expander-compressor pair at 350 MHz with a 3 dB bandwidth of approximately 11 MHz, an overall bandwidth of approximately 33 MHz, and a chirp time of 1.0 ps was designed . The sidelobe suppression in the design is better than 40 dB. The measured filters exhibit a sidelobe level close to -40 dB. Design and measurement are in excellent agreement.
• A. Pohl, F. Seifert, L.M. Reindl, G. Scholl, T. Ostertag, W. Pietsch
  Radio signals for SAW ID tags and sensors in strong electromagnetic interference
  1994 Proc. IEEE Ultrasonics Symp., pages: 195 - 198
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  Abstract

  The applicability of wirelessly interrogated passive IDtag type SAW sensors for measurements of the temperature of disc brakes of moving railway cars is shown. Here, a short radio channel allows relatively simple radio impulse processing by phase evaluation. Further, using elastic convolver measurement in large steel works, we discuss the feasibility of passive SAW sensors in a severely obstructed radio channel with interference. For such environments radio signals of the spread spectrum type and a receiver with the corresponding correlative SAW structure or a RAKE receiver are appropriate for remote readout,
• F. Schmidt, O. Sczesny, L.M. Reindl, V. Magori
  Remote sensing of physical parameters by means of passive surface acoustic wave devices ("ID-TAG")
  1994 Proc. IEEE Ultrasonics Symp., pages: 589 - 592
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  Abstract

  A system for remote measurement of numerous physical quantities with passive sensors is presented. It consists of a radio frequency interrogator with evaluation electronics and a surface acoustic wave (SAW) device used as a sensor. For practical tests, an interrogator has been developed, which is able to read commercial identification SAW-tags. As an example, the relative position and temperature of the SAW element have been derived from the received data. The temperature resolution proved to be about 0.1 "C within a range of -20 "C to +140 "C, the distance resolution is about 5 millimeters. The detection distance is up to 15 meters for 5 watts output peak power. The promising results indicate that using this technique remote sensing of many physical parameters is feasible. The sensors are wireless and do not require a power supply, so measurements in dangerous, radioactive or dirty environment or from moving or rotating objects becomes obtainable.

1993

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• J. Machui, G. Müller, W. Ruile, L.M. Reindl, R. Weigel, P. Russer
  A new loss SAW filter structure with extremely wide bandwidth for mobile communication systems
  1993 IEEE MTT-S International Microwave Symposium Digest, pages: 1501 - 1504
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  Abstract

  We present a low loss surface acoustic wave (SAW) filter with a dual–track configuration which is characterized by a new arrangement of interdigital transducers (lDTs) and reflectors in each acoustic track as well as a special electrical connection of the IDTs. Broadband filter characteristics can easily be achieved by using chirped components. The inherently good stopband rejection of the new structure has been further improved by applying proper weighting techniques to the IDTs and reflectors. A filter with a relative bandwidth of 10 % and a center frequency of 200 MHz has been designed by means of a new synthesis method. The filter has been fabricated on 128° Y–X LiNb03. We measured a minimum insertion loss of 4 dB, a small passband ripple of about 1 dB, and a stopband rejection better than 35 dB. Excellent agreement between simulation and measurement has been found.
• R. Weigel, G. Müller, J. Machui, W. Ruile, L.M. Reindl, P. Russer
  Low-loss broadband SAW two-track reflector filter using chirped structures for mobile radio applications
  1993 Asia-Pacific Microwave Conference APMC '93, pages: 16, 59 - 63
• A. Fauter, L.M. Reindl, R. Weigel, P. Russer, F. Seifert
  Miniaturized SAW convolver for indoor mobile communication
  1993 Proc. IEEE Ultrasonics Symp., pages: 73 - 77
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  Abstract

  Design and performance of a miniaturized prototype SAW convolver on YZ-LiNbO3 are reported. The small and compact device fits into an SMD package of size 18 x 8.2 x 2.4 mm³. Output summing is realized with two bond wires, and external matching circuitry incorporates only simple lumped elements such as SMD components and copper coils. At a center frequency of 350 MHz, an integration time of 3 µs and a bandwidth of 50 MHz, i.e. a time- -bandwidth product of 150, have been obtained. The achieved efficiency of -70 dBm • 0.5 dB may be improved considerably. The deviation from linear phase was less than ± 50. Uniformity and corresponding phase were within ± 0.5 dB and • 50, respectively.
• L.M. Reindl, W. Ruile
  Programmable reflectors for SAW-ID-tags
  1993 Proc. IEEE Ultrasonics Symp., pages: 125 - 130
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  Abstract

  Surface acoustic wave devices for identification systems (SAW-ID-tags or SAW wireless labels) have a large potential for future applications. We concentrate in this paper on reflective SAW-IDtags with amplitude modulation. We use splitfinger interdigital transducers as reflecting structures. If the transducers are short circuited or capacitivly loaded the reflection disappears almost entirely. On the other hand, if an open circuit or inductive load is used, the lDTs reflect incoming SAWS. The coding of the reflectors can therefore be done once and for all by a, e.g., photolithographic process or, alternatively, programmable by external circuitry. This new possibility of dynamic programming can be used to transmit time dependent data. We present basic considerations on the design and measurements of prototypes of SAW-ID-tags on YZLiNbOS at 285MHz and 2.45GHz.
• K. C. Wagner, L.M. Reindl, O. Männer
  Surface wave to bulk wave conversion in SAW-reflectors on strong coupling substrates
  1993 Proc. IEEE Ultrasonics Symp., pages: 209 - 213
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  Abstract

  Reflective structures consisting of arrays of single or interconnected metallic strips exhibit surface to bulk wave conversion at frequencies above a certain threshold frequency. The resulting attenuation of the reflected SAW-signal due to bulk wave losses is of concern, if either very low loss (VLL) filters have to be built, or if a well defined, potentially small amount of reflectivity is desired. In contrast to traditional simulation methods for reflectors, we employ a self-consistent approach based on the Green's function formalism. Its main advantage is the fact that the finite extent of the grating as well as surface wave - bulk wave interaction are both taken into account accurately. We discuss the bulk wave conversion properties of open, shorted and mixed (so called open-shorted) finite reflectors made of strips in strictly periodic or chirped arrangement, and the design of bulk wave conversion gratings.

1991

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• E. Mayer (Garova), V.I. Grigorievsky, A.P. Kundin, V.P. Plessky
  RAC on SAW with long delay time (in Russian)
  1991 Leningrad XV Soviet Conference on Acoustoelectronics and Physical Acoustics of the Solid State, volume: 3, page: 64
• E. Mayer (Garova), V.P. Plesskii
  Reflection and scattering of Gulyaev-Bleustein waves at a resonant element
  1991 J. Advanced Sci. (Japan), volume: 3, issue: 33, pages: 141 - 144
• E. Mayer (Garova), V.P. Plessky
  Scattering of Rayleigh waves at a heavy strip (in Russian)
  1991 Leningrad XV Soviet Conference on Acoustoelectronics and Physical Acoustics of the Solid State, volume: 2, pages: 14 - 15
• L.M. Reindl, N. Brutscher
  The intrinsic source-impedance of SAW-convolvers
  1991 Proc. IEEE Ultrasonics Symp., pages: 117 - 122
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  Abstract

  An analysis of the power flow in a Surface Acoustic Wave (SAW) convolver leads to a clear picture of the influence of the different physical effects. It is shown how, at the output port, the acoustoelectric conversion of the power generated by nonlinear effects contributes to the total efficiency of the convolver. An equivalent circuit model allows to describe this process in a very straightforward manner. It will be demonstrated how the elements of this model can be calculated and measured. Finally, we discuss a version of Fano's lirnit that takes Ohmic resistance effects into account. Our approach is validated by measurements of the source impedance of different convolvers. These measurements show good agreement with the computations.

1989

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• C.C.W. Ruppel, C. Kappacher, G. Visintini, L.M. Reindl
  Design and compensation of non-eqidistantly sampled SAW transducers
  1989 Proc. IEEE Ultrasonics Symp., pages: 19 - 23
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  Abstract

  We present a non-iterative algorithm for the design of non-equidistantly sampled interdigital transducers (IDT). This method allows the precise design of IDTs with a given impulse response. Deviations according to the impulse model are less than .1 dB within the passband. Additionally, we show the design and the compensation of second order effects of a delay line with two chirped and apodized IDTs and the measurement of this filter.
• E. Mayer (Garova), V.P. Plessky, Yu.A. Sidorenko
  Rayleigh wave propagation in a reflective structure with slowly varying period
  1989 Varna, Bulgaria II International Symposium on Surface Waves in Solids and Layered Structures, volume: 2, page: 305
• H.P. Graßl, L.M. Reindl, C.C.W. Ruppel, H. Zottl
  Surface acoustic wave passive devices for spread spectrum systems
  1989 Erlangen, Germany Proc. URSI (International Union of Radio Science) International Symposium on Signals Systems and Electronics

1988

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• I. Schropp, L.M. Reindl, H. P. Graßl, R. Weigel
  Accurate prediction of dispersion and attenuation of long metal strip SAW waveguides on anisotropic substrate
  1988 Proc. IEEE Ultrasonics Symp., pages: 263 - 267
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  Abstract

  As a design tool for high precision long broadband SAW delay lines a computationally simple model for shorting strip waveguides has been improved by inclusion of parametric fits to measured anisotropy, dispersion, and attenuation of Rayleigh wave propagation both on free and metalized surfaces of LiNbO3. A heuristic approach was used to account for the effect of anisotropy in the case of imaginary transverse propagation constant, and for the observed increased attenuation in waveguides compared to unbounded surfaces. The model does not rely on material properties as computed from fundamental material constants, and uses only one adjustable parameter which is not directly obtained from surface wave measurements. The phase nonlinearity can be predicted with an accuracy up to +/-0.5"/ps over a relative bandwidth on the order of 50%.
• E. Mayer (Garova), V.P. Plessky, Yu.A. Sidorenko
  Influence of multiple reflections and technological defects on the RAC characteristics (in Russian)
  1988 Kishinev XIV Soviet Conference on Acoustoelectronics and Physical Acoustics of the Solid State, volume: 2, pages: 117 - 119

1987

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• L.M. Reindl, H.W. Wörz, H.P. Graßl
  CAD of precise SAW convolvers and long delay lines
  1987 Proc. IEEE Ultrasonics Symp., pages: 85 - 89
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  Abstract

  A CAD procedure for the optimization of highly efficient, precise, and mass producible convolvers with narrow aperture chirp transducers based on all-planar technologies is described. Convolvers are fully modeled in the computer. Nonlinear-chirp transducers are used to correct for all distortions due to matching networks and acoustic waveguides. Examples are presented of a broadband convolver with a time-bandwidth-product of 2600, an 80 MHz dual channel convolver for BOK signals, and an acoustic waveguide delay line with BT = 6650 using the same design principles as the convolvers.

1986

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• E. Mayer (Garova), V.P. Plessky
  Distortion of the phase-frequency characteristics of RAC, connected with multiple reflections of SAW in gratings (in Russian)
  1986 Chernovcy XIII Soviet Conference on Acoustoelectronics and Physical Acoustics of the Solid State, volume: 2, pages: 258 - 259

Other publications

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2015

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• Al. Richter, Ph. Klein, F. Tautz
  Bird Monitoring by Wireless Networks
  Wearable Computing Systems Seminar, Freidok, University of Freiburg, 2015

2014

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• Fischer S., Goldschmidt J.C.
  Using the full solar spectrum with upconverter devices
  SPIE newsroom, 2014

2013

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• A. Bannoura, C. Ortolf, C. Schindelhauer, L.M. Reindl
  The Wake Up Dominating Set Problem. Technical Report 273, Department of Computer Science, University of Freiburg
  , 2013
• A. Bannoura, O. Gorgis, L. Reindl, C. Schindelhauer
  Time Analysis for Wireless Wake-Up Radio Transceivers. In Proceedings of 16. Internationaler Kongress für Sensoren und Messtechnik (SENSOR 2013)
  , 2013

2012

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• Q. Hamp
  Arbeitspaket 2: SOP-gestütztes Informationssystem, I-LOV Projekt Schlussbericht
  IMTEK, Freiburg, Germany, 2012
• Q. Hamp, L.M. Reindl
  I-LOV Projekt Schlussbericht
  IMTEK, Freiburg, Germany, 2012

2009

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• M. Freunek(Müller)
  Zuverlässigkeit von Modulen für die Gebäudetechnik
  ep Photovoltaik, volume: 11-12, pages: 43 - 44, 2009