Reduced-Order Modal Solution of the Full-Wave Method of Moments Based on a Quasi-Static Eigenvalue Approach

A modal solution of the full-wave Method of Moments (MoM) based on a quasi-static eigenvalue problem is presented. The resulting modal current solutions have to be determined only once and serve as a global basis and test functions. Since only the resonant modes within the frequency bandwidth of interest are required, the system order can be significantly reduced. It is shown how the contribution of the remaining modes can be determined by a single quasi-static calculation. In addition, by extracting the divergence-free modes, the typical low-frequency breakdown of the MoM is eliminated. Furthermore, the modal solution provides also a physical insight into the system behavior.

I. Introduction

Numerical simulation of passive linear systems, such as interconnection structures, antennas, or metallic enclosures, has become an integral part of the design process of electronic systems in order to achieve EMC compliance, signal, and power integrity and to assess radiated emissions. A widely used numerical method, especially when dealing with radiating structures, is the Method of Moments (MoM) [1]. However, the order of the MoM-system matrix can become very high when complex geometries with large surfaces are considered, resulting in high computational effort and memory requirements for solving the corresponding system of equations.