ABSTRACT
In this chapter, the authors consider the general properties of hollow metallic waveguides, with simply-connected boundaries. First they study the simple, though highly idealized, case of a parallel-plate waveguide, which exhibits many of the important properties common to all metallic guides, and then they proceed to consider waveguides of arbitrary cross-section. Two methods for analyzing special cross-sectional shapes will be discussed: separation of variables, and the ray method. Only a few special cross-sectional shapes permit exact determination of the mode fields and eigenvalues of a hollow waveguide by separation of variables. It is desirable to have some general principles from which they can deduce some approximate characteristics of modes for any shape of waveguide, and gain some physical insight into the guiding mechanism as well. For this purpose, they consider another method by which some types of hollow metallic waveguides can be exactly analyzed: the ray approach which was used for the parallel-plate waveguide.
