Frequency Response Characterization of Surface Acoustic Wave Resonators Using a Six-Port Frequency Measurement System

Surface acoustic wave (SAW) resonators can be used in several fields as passive radio frequency (RF) sensors. By measuring the actual resonance frequency, different parameters as strain, torque or temperature can be captured even in harsh environments. Even though the resonators can be processed very cheaply, today's commercially available readers are costly and consume a lot of power due to powerful calculation units and fast analog-digital-converters (ADCs). Recently, the instantaneous frequency measurement (IFM) with a six-port interferometer has shown to be a promising low-cost and low-power approach. As the resonator has to be excited close to its resonance frequency the frequency response has to be known at first. To solve this problem, a fast process for the characterization of the frequency response of surface acoustic wave (SAW) resonators using a low-cost six-port based frequency measurement system is described in this publication.