Scattering at rectangular-to-rectangular waveguide junctions

This short paper presents formally exact solutions with convergent numerical results to the problems of scattering from a rectangular-to-rectangular waveguide junction and from a thick diaphragm with rectangular aperture in rectangular waveguide. The method uses normal mode expansions of the waveguide fields and the principle of conservation of complex power. A variety of configurations are considered and numerical convergence is confirmed by comparison with experiment.