Analysis of waveguides with dielectric inserts

A unified method for analyzing complex microwave systems which involve different guiding structures is presented. The method depends on applying the equivalence principle to replace the dielectric insert by electric and magnetic surface currents. The field excited by these currents is then expanded with respect to the eigenmodes of the corresponding empty waveguide. The yet unknown electric and magnetic surface currents are expanded with respect to properly chosen basis functions, and the continuity of the field across the air-dielectric interface(s) is tested by the same functions. The validity of the method is checked by analyzing a simple dielectric-slab-loaded rectangular waveguide. The method is then applied to the analysis of more complicated structures, e.g. shielded dielectric image guide and shielded dielectric rod guide.<>