Introduction
INTRODUCTION
The accurate analysis and design of complex microwave devices is a fundamental requirement in the area of applied electromagnetics. Typically, two approaches are employed to this aim: the analytical and the numerical one. In the former case the advantage of a rigorous method is compensated by the limited availability of known solutions for few simple cases. In the latter approach, the improvement of the computational capability and the memory availability of the computing resources, allow us to implement several efficient numerical methods. All these methods have an additional degree of generality with respect to the analytical approach: for instance, they can account for a discontinuity of arbitrary shape and compute any component of the electromagnetic field at any place of the computational domain by solving the integral-differential equations with proper boundary conditions. The hybridization of more than one numerical method allows us to compensate the drawbacks of a technique with the advantages of the other one.
The topic of this work concerns the electromagnetic analysis of periodic devices with finite or infinite dimensions and their combination, by using the hybridization of the Finite Element Method (FEM) and the Mode Matching (MM) Method with genetic optimization procedure and spectral decomposition approach.
In particular the Mode Matching method (a GSM-based approach) and the Finite Element Method are presented in Chapter 1. Consequently the hybridization of the MM-FE is illustrated underlining the advantages and the drawback of both technique.
In Chapter 2, an optimization procedure for inductive Frequency Selective Surfaces (FSSs) is presented, which is based on the use of the Genetic Algorithm (GA). The GA synthesis procedure involves an electromagnetic solver based on the combination of the Mode Matching method and the Finite Element Method (MM-FEM). Some numerical results are shown to validate this approach.
In Chapter 3, the hybrid method MM-FE combined with the Spectral Decomposition is applied to the study of large finite arrays of waveguide apertures. In particular the methodology for analyzing array of rectangular open-ended, iris-loaded waveguides and horn antennas is presented. Some numerical results, compared with those available in literature and those obtained by using commercial softwares, are shown.
In Chapter 4, an extension of the SD approach is applied to the study of finite thin FSSs.
The SD approach is hybridized with a MoM procedure for thin structures.
Finally, Chapter 5 presents the application of the MM-FEM-SD to the study of a finite array of waveguides combined with a finite thin FSS with different periodicity.
1
