Advanced Electromagnetic Numerical Modeling Techniques for Various Periodic and Quasi-Periodic Systems

Abstract

This dissertation is mainly concerned with several advanced electromagnetic modeling techniques for practical complex systems, which involve periodic analyses. The focus is to reveal the physics of the electromagnetic wave interaction with the complex structures, and also to arrive at improved computational algorithms. This dissertation consists of three self-contained parts, each discussing one modeling technique. Examples presented in this dissertation include (a) an analysis of conductor surface-roughness effects, (b) a novel model for vertical interconnects (vias) and (c) a leaky-wave study of a Fabry-Perot resonant cavity antenna. The first part investigates conductor surface roughness effects for stripline. An equivalent rough-surface-impedance is extracted using a periodic full-wave analysis and is then used for the modification of the transmission line per-unit-length parameter. The second part proposes a semi-analytical analysis for massively-coupled vias with arbitrarily-shaped antipads, based on the reciprocity theorem. The use of reciprocity yields simple design formulas and is seen to greatly improve the computational efficiency, due to the fast-converging mode-matching calculation. The third part presents a leaky-wave study of a Fabry-Perot cavity antenna made from a patch array. The patch current densities are calculated using the array scanning method. Based on this, a "leaky-wave current" is defined and calculated using residue integration. In addition, the radiation properties of a large finite-size array (truncation effects) are evaluated. All three proposed models are verified by full-wave simulations and/or measurements. Numerical results prove the effectiveness and accuracy of these models.Electrical and Computer Engineering, Department o