Experimental Distinction Between Crossed-Field and In-Line Three-Port Circuit Models for Interdigital Transducers (Short Papers)

The crossed-field and in-line Mason circuit models for interdigital surface-wave transducers give opposite predictions for the dependence of acoustic reflection coefficients on electric load resistance for purely resistive loads. Experiments described herein show that the crossed-field model correctly describes the reflections for YX quartz, ST-X quartz, and YZ lithium niobate substrates. A low-resistance load minimizes reflections for transducers with double electrodes operating at the fundamental synchronous frequency. For single electrode transducers, optimum reflection suppression may call for a load resistance comparable to the transducer impedance.