Multimode analysis of rectangular waveguide transitions

A method is presented to calculate the multimode scattering matrix of a continuous tapered rectangular waveguide transition. The method is based on approximating the transition by cascaded uniform waveguide sections, determining the scattering matrices of their junctions by a mode-matching method, and combining the matrices to yield the overall scattering matrix. The effect of non-propagating modes is included. Twocriteria for convergence and a numerical example are given