Parameters in the coupling-of-modes equations for a natural single-phase unidirectional transducer and a transduction center shift reversal of directivity transducer on a La3Ga5SiO14 substrate

Parameters included in coupling-of-modes equations such as coupling coefficient, transduction coefficient and electrode capacitance are theoretically determined using the finite-element method (FEM) for a natural single-phase unidirectional transducer (NSPUDT) and a transduction center shift reversal of directivity transducer (TCS-RDT) on La3Ga5SiO14 piezoelectric single crystal which has a higher electromechanical coupling coefficient compared to quartz. The electrode thickness dependance of the parameters and the excitation characteristics of NSPUDT and TCS-RDT are investigated in detail. For NSPUDT, the parameters obtained by the present method are compared with those obtained by the perturbation method. Furthermore, numerical results for the frequency characteristics of NSPUDT are compared to the experimental data, and the validity and usefulness of the present method are demonstrated.