Quartz orientations for optimal power efficiency in wireless SAW temperature sensors

The efficiency of electromagnetic power re-radiation by a wirelessly interrogated passive sensor and its sensitivity to the measured value are the main factors defining the sensor performance. The analysis gives the relation between the re-radiation efficiency and the electromechanical coupling factor. Experimental resonator parameters demonstrate the relevance of this efficiency improvement. The calculation of the coupling factor simultaneously with the temperature coefficient of delay for all quartz orientations was carried out. The results of this calculation can help to select optimal trade-offs between the sensitivity and the efficiency of power re-radiation.