Efficient integral equation formulations for admittance or impedance representation of planar waveguide junctions

In this paper we describe very efficient impedance and admittance Integral Equation (IE) formulations for the study of passive microwave devices composed of cascaded uniform waveguide sections. The formulation leads directly to reduced multimode matrix representations that only involve a small number of accessible, or interacting, modes. In addition to theoretical results, a performance comparison is also discussed which clearly demonstrates the improvement achieved.