Efficient numerical/analytical approach for electromagnetic modeling of quasi-planar structures

This dissertation presents a study of analytical and numerical techniques aimed at extending the applicability of spectral domain electromagnetic modeling to a broad class of problems including electrically large structures, and locally planar components interacting with a nonplanar scattering environment.; The objective is to develop methods of combining numerical and analytical techniques in an optimum manner to achieve an appropriate level of accuracy, while minimizing computational cost. The Method of Moments is the starting point for our numerical procedure. The analytical techniques to be used in combination with the moment method include asymptotic approximation and complex contour integration approaches that significantly predate the field of numerical electromagnetics. The larger goal for the resulting “hybrid” methods is not only to generate efficient simulation code, but also to increase physical insight that will support innovative design.; The foundation of our study is the spectral domain approach, and the associated rigorous Green's functions for multilayer structures. The method of moments, formulated in the spectral domain, has proven useful for the analysis and design of multilayer printed circuits and antennas. The approach is strictly applicable only to transversely infinite planar substrates in the standard formulation, and is practically limited in terms of electrical size. In this work we develop methods to extend the applicability of the method to address the effects of nonplanar surroundings, and to improve efficiency when analyzing large structures. We incorporate geometrical optics ray-tracing in the moment method solution and demonstrate the accuracy and efficiency of this approximation. We also introduce a rigorous modal expansion method applicable to arbitrary closed structures, and demonstrate its validity in the analysis of a cylindrical cavity.; Potential applications for these techniques include antenna integration and compatibility studies on complex platforms such as aircraft and ships; cavity-backed antenna design; large but finite antenna arrays; packaging problems; and finite planar substrates.; The analytical/numerical formulation presented in this dissertation establishes a general foundation for the integration of different numerical electromagnetic codes. Different parts of a complex physical structure may be optimally simulated using computational techniques appropriate to each part, and then combined together using the basic numerical/analytical model developed here.