SAW-based radio sensor systems

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 sens...

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Bibliographic Details
Published in:IEEE sensors journal 2001-06, Vol.1 (1), p.69-78
Main Authors: Reindl, L.M., Pohl, A., Scholl, G., Weigel, R.
Format: Article
Language:English
Subjects:
Magnetic field measurement
Pressure measurement
Radar antennas
Radio frequency
Sensor systems
Surface acoustic waves
Temperature sensors
Transceivers
Transponders
Wireless sensor networks
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Summary: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. The 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 occurs, due to the high delay time of the SAW transponder, on the order of some microseconds. This 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. (Author)
ISSN:1530-437X
1558-1748
DOI:10.1109/JSEN.2001.923589