Simulation of bulk wave effects in SAW devices using Green´s function and angular spectrum of waves

It is shown that the angular-spectrum-of-waves formalism can be used for the calculation of spurious bulk-wave transmissions in SAW (surface acoustic wave) devices. For each SAW-propagation direction, the bulk-wave contribution to the Green´s function is approximated by a sum of several decaying sinusoidal waves. Applying a least-squares fitting procedure, the a priori unknown amplitudes, phases, and decay constants are determined. These data are used as input for an analysis program based on the extended angular-spectrum-of-waves formalism. Advantages of this approach are correct consideration of angle-dependent coupling and bulk-wave diffraction, compatibility to SAW-device analysis based on angular-spectrum methods, and moderate CPU-time requirements