TABLE OF CONTENTS For many electromagnetic structures, exact analytical solutions cannot be found. It is therefore necessary to consider numerical methods to obtain approximate solutions of field problems. A great variety of methods for electromagnetic field modeling has been developed [1 3]. In order to obtain results of the required accuracy with a minimum of computational effort, a method matched to the problem has to be chosen. The optimum design of radio-frequency devices, circuits and systems strongly depends on the availability of advanced computer- aided design (CAD) tools for modeling and optimization.
The method of moments (MoM) plays a crucial role in numerical electromagnetics [4 6]. In the MoM the field functions are expanded into series of basis functions. The problem of solving partial differential equations or integral equations for the field functions is converted into the problem of solving linear systems of equations for determining the coefficients of the series expansions of the field functions. Within the methods for field computation the MoM holds a special position since most of the methods of field computation - for example the integral equation method, the spectral domain method, the partial wave synthesis, the transmission-line matrix method and the finite difference method - may be considered in connection with the MoM. MoM is a very general scheme for the discretization of the field problem, whereas the other methods specify in detail how the discretization is performed.
Table 14.1 lists some of the most widely used methods for electromagnetic field computation [1].
