A coupling-of-modes analysis of chirped transducers containing reflective electrode geometries

An accurate and numerically efficient model for analyzing chirped transducers incorporating internal reflections is presented. The model results in a complete three-port characterization of the transducer. The three-port description of the transducer (two acoustic ports and one electric port) is obtained by representing the response of the chirped 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. The solution for the transducer´s acoustic admittance, a quantity not previously documented in the literature, is included. For verification of the analysis technique, experimental results for a pair of linearly chirped transducers fabricated on 34° quartz are presented. These transducers include a conventional two-electrode per-wavelength transducer and a single-phase unidirectional transducer (SPUDT). Excellent correlation between the theoretical solutions and the experimental measurements is shown