An Electrostatic Voltage Sensor Using Surface Acoustic Waves

Abstract

A compact electrostatic voltage sensor has been developed with a frequency modulated surface acoustic wave (SAW) delay-line oscillator. The SAW delay-lie oscillator was constructed with piezo- electric ceramics and a 128 deg rotated Y-cut LMb03 substrate on which an additional collector electrode is fabricated. The electrostatic voltage applied to the collector electrode is detected by the frequency change of the SAW oscillator. The center frequency of the SAW delay- line oscillator was chosen to be 23 MHz for piezoelectric ceramics and 39.6 MHz for LiNb03. A vibrating modulator was also applied to the collector electrode. An FM signal modulated by a vibrating electrode was obtained from the SAW oscillator. The FM signal was demodulated with an FM demodulator.