A Coupling-of-Modes model for SAW Transducers with Arbitrary Reflectivity Weighting

An accurate and numerically efficient model for SAW devices incorporating transducers with non-uniformly weighted internal reflections has been developed. The model describes each of the device\u27s transducers using a three port characterization (two acoustic ports and one electric port). These three port descriptions are combined to obtain the complete device\u27s description. The three port description of a transducer is obtained by representing the response of the non-uniform transducer as that of a set of cascaded uniform sections. The three port solutions for a uniform section of transducer are presented as the results of a coupling-of-modes (COM) analysis. These solutions include the transducer\u27s acoustic admittance, a quantity not previously documented in the literature. For verification of the analysis technique, experimental results for a single phase unidirectional transducer (SPUDT) filter are presented. The filter\u27s insertion loss, triple transit suppression, and out-of-band rejection are all found to agree well with the theoretical predictions