Optimization of composite transducer designing in high frequency applications

The main obstacle to constructing a wide bandwidth and high frequency composite transducer comes from its internal vibration field fluctuation, which is aggravated as frequency increases. We found an optimized structure of 2-2 composite in which the vibration field in both phases remains nearly uniform over a wide frequency range and the piezoelectric coupling coefficient reaches its maximum value simultaneously. This article also proposes a modified representation to calculate more precisely the effective piezoelectric coupling coefficient when the vibration fluctuation has been taken into account.