8E-1 A Technique for P-Matrix Computation by Periodic FEM/BEM Analysis

Abstract

An extension of the periodic FEM/BEM analysis technique is proposed and its application to P-matrix computation for periodic grating structures is described. Conventional BEM is extended to include waves propagating in opposite directions. The FEM part is extended to include power flow through the periodic boundaries, where the fields are expressed as linear combinations of known propagating modes. The modes for the given device structure can be calculated by the conventional FEM/BEM analysis. The action integral for the FEM is given in which the displacement and the electrostatic potential are treated as complex fields. It is shown, based on Noether's theorem, that the power flow through the boundaries derived from the given action integral is described by surface integral of the Poynting vector. P-matrix elements can be obtained as part of solutions for the combined FEM/BEM equations.

Periodic Analysis of Surface Acoustic Wave Resonator with Dimensionally Reduced PDE Model Using COMSOL Code

“…Thus, many researchers focus on the finite element analysis of periodic structures, which give rise to a significant reduction in the size of the numerical model and yield useful information for the whole resonator [ 29 , 30 , 31 , 32 ]. Among them, the periodic analysis based on FEM/BEM provided an effective way to accurately simulate the useful information of a normal SAW resonator [ 33 , 34 , 35 ]. Nevertheless, this method requires a long time to compute the Green function, especially for the multi-layered and intricate structure of SAW resonator, the Green function calculation in BEM becomes complex or even impractical.…”