A Novel Preconditioning Technique and Comparison of Three Formulations for Hybrid FEM/MoM Methods

Abstract

Hybrid FEM/MoM methods combine the finite element method (FEM) and the method of moments (MoM) to model inhomogenous unbounded problems. These two methods are coupled by enforcing field continuity on the boundary that seperates the FEM and MoM regions. There are three ways of formulating hybrid FEM/MoM methods: outward-looking formulations, inward-looking formulations and combined formulations. In this paper, the three formulations are compared in terms of computer-resource requirements and stability and four sample problem geometries. A novel preconditioning technique is developed for the outward-looking formulation. This technique greatly improves the convergence rate of iterative solvers for the type of problems investigated in this study.