Scattering at junction between a small coaxial line and a large rectangular waveguide

This paper presents a formally exact solution (mode-matching method) to the problem of scattering at the junction between a small coaxial line and a large rectangular waveguide. The eigen-mode functions for both coaxial line and rectangular waveguide are used to express the field components in both regions and the transverse field components are then matched to obtain the scattering parameters of the waveguide junction. The E-field mode-matching matrix is analytically derived in closed-form for efficient computation. Numerical results for a few waveguide problems involving the coaxial line-to-rectangular waveguide junction are presented and discussed. The mode-matching method results are in excellent agreement with those obtained by Ansoft's HFSS and the method has high computation efficie