Hybrid finite element/moment method solution of two-dimensional scattering problems

Abstract

Describes the solution of a two-dimensional scattering problem that consists of a strip embedded in the coating of infinite ground plane containing an aperture that is backed by a cavity. The cavity may be arbitrarily shaped and inhomogeneously filled. The problem under consideration consists of two distinct regions. The external region is very well suited to solution via spectral-domain moment method (MoM). Due to its geometric and material complexity, the internal region is best treated using a partial differential equation (PDE) technique such as vector (edge element) FEM. Clearly, solution of the entire problem with either technique alone is likely to be very difficult and to generate a numerical model that is very computationally intensive, inaccurate or both. An exception to the above statement occurs when the cavity is homogeneously-filled and its cross-section is rectangular. Results from this special case are used to validate the hybrid approach involving both methods. The system of equations generated by the hybrid method can be viewed as the concatenation of a small dense system (from MoM) with a large sparse system (from FEM). This partially sparse, partially dense system is solved using a costume biconjugate gradient routine which is specifically designed for the system generated by the hybrid method.