A contour-integral matching method for the analysis of metallic and dielectric waveguides of arbitrary cross-section

A rigorous numerical method is presented for analyzing the modal characteristics of metallic and multi-step dielectric waveguides of arbitrary cross-sections. The approach makes use of a Fourier-Bessel expansion for the field and imposes the boundary conditions via a line integral extended over the closed boundary contour. Results are presented for the dominant-mode cutoff wavenumbers of several metallic waveguides of different cross-sections and for the propagation constants of the two fundamental modes of a rectangular dielectric waveguide. These examples prove the approach to be both accurate and computationally efficient.