Combined scattering matrix and boundary integral equation method for the analysis and field computation in three-dimensional multiport waveguide discontinuities

This paper discusses the analysis and numerical computation of time-harmonic electromagnetic fields in arbitrarily shaped three-dimensional waveguide discontinuities and junctions. The waveguides meeting at the junction may have different cross-sections. The developed method combines the boundary integral equation method, used for the discontinuities, with the analytical waveguide solutions. The RWG-functions are applied as basis and test functions in the method of moments solution of the electric field integral equation. In addition, all field solutions on the waveguide discontinuities are efficiently characterized by the scattering matrix of a multiport waveguide system. In a two-port case, for example, only two field solutions are required to determine all possible wave forms. The accuracy of the developed method is verified by considering numerical examples.