Material, geometry, and frequency independent bivariate universal functions for the analysis of mechanical and electrical loading effects in acoustic devices: A Fast-MoM approach

In this paper we consider the massloading problem in surface acoustic wave devices under fairly general conditions. We assume a finite number of non-equidistantly spaced electrodes with arbitrary cross-section geometries and material constitutions. Electrical loading effect is also addressed and a model is presented which is a generalization of this author´s model published in 1989. To solve our problem we have considerably improved the capabilities of the Fast-MoM analysis technique. It turns out that it is possible to generate bivariate universal functions which are frequency, material, and geometry independent. The purpose of this paper is to provide an idea about how the universal functions are created. Having the universal functions we simply have to follow the following recipe to solve a practical problem: (1) discretize the boundaries of electrodes; (2) find the positions of a number of sampling points; (3) sample the universal functions; (4) construct a square matrix; (5) solve a system of equations. If the frequency, or the material, or the geometry of an electrode alters only the locations of the sampling points change. In this paper we present examples for the universal functions and discuss one application of the Fast-MoM.