Analysis of waveguide discontinuities using eigenmode expansion

A novel semi-analytical modal formalism is developed utilizing known solenoidal and irrotational cavity eigenmodes to solve electromagnetic scattering inside waveguides. The proposed approach is based on the use of modal expansion of fields to solve Maxwell's equations, in conjunction with a convenient choice of port boundary conditions, which results in an eigenmode projection problem. With the help of the generalized scattering matrix (GSM) approach, waveguides discontinuities loaded with arbitrary dielectric profiles can easily be analyzed. Convergence studies show consistent solutions for a small number of expansion modes.