Resonator Substrate-Integrated Waveguide (SIW) Sensor for Measurement of AC Electric Fields

In this paper, a wireless, passive electric field sensor that is based on a substrate-integrated waveguide (SIW) resonator is designed, fabricated, and evaluated. When exposed to an external electric field, the resonance frequency of the resonator shifts due to the variation of the capacitance of a diode varactor that is mounted on the sensor. The sensor is designed to work in the ISM band and demonstrates a high loaded quality factor of more than 200. An interrogation system has been developed that is capable of rapidly measuring the resonance frequency of the resonator and determine the waveform of the external electric field at a rate of 100 kHz. The interrogator sends pulses of radio frequency signals to the sensor and determines the resonant frequency from the ring back that is emitted by the resonator.