Full-wave 3D analysis of wave scattering on SAW-structures with finite aperture

The interaction of surface and bulk acoustic waves with arbitrarily shaped electrodes of finite aperture and negligible thickness, located on the surface of a piezoelectric substrate is analyzed. The reflectivity of a finite number of coupled electrodes is calculated. The reflectivity calculations take into account the following: (i) the 2D geometry of the electrodes involved, (ii) the frequency, (iii) the angle, and (iv) the profile of the incident beam in multi-strip coupler calculations. The conversion of surface waves into bulk waves, as a result of wave interaction with the electrodes, is investigated. It is found that previous models are sufficiently accurate in the frequency range above the fundamental frequency. However, scattering parameters have to be corrected at lower frequencies. The acoustic and the electric scattering parameters for electrodes on YZ-LiNbO₃-substrate are calculated