Characterization of matched piezoelectric transducer bars

Abstract

To aid the design of linear arrays, it is quite important to have a detailed understanding of the elementary transducer behavior. These transducer bars must be backed and matched. The aim of this work is to characterize and to optimize layers that are used to match such transducer bars. In order to show the influence of these layers, the acoustical (acoustical power, far-field directivity pattern), electrical (electrical impedance) and mechanical (displacement field) parameters of the transducer are computed using the finite element method. Numerical studies of several transducers with different ideal matching layers which satisfy the one-dimensional criterion are presented and carefully analyzed. These studies show the existence of parasitic modes in the desired operating band of the transducer, due to shear wave propagation in the matching layer. A simple choice criterion of the matching material suggesting no parasitic mode in the desired operating band of the transducer bar has been defined. This criterion is given by W