6D-3 Simplified Green Function Techniques for General SAW Device Analysis and Optimization

In recent years, the Green function, or boundary element (BEM), method has become the preferred technique for rigorous SAW device analysis. However, because of its computational cost, its principal application has been the analysis of mode propagation in periodic structures to determine parameters that can then be used in simplified coupling of modes (COM) or P-matrix models. This paper describes methods for approximate Green function analysis that can combine high accuracy with modest computational cost. Green function approximations are derived by a judicious choice of discrete modes to characterize the continuous mode spectrum, and by restricting the number of independent displacement components employed. The resulting procedure is efficient enough to be applied directly to the analysis and optimization of components such as LCRFs (longitudinally coupled resonator filters), using either leaky wave or surface wave modes