Fast algorithm for the characterization of ridged waveguide discontinuities

Ridged circular waveguide discontinuities are used in many applications such as polarizers and filters. This paper presents a fast algorithm for their characterization. The method is based on integral equation with a scalar Green's function for the calculation of mode spectrum of ridged circular waveguide, in combination with an improved variational multimodal formulation for the characterization of the step discontinuity. The coupling coefficients are evaluated by post-processing of the matrices already used in the mode determination. The overall scattering matrix is obtained by cascading an impedance matrix of each discontinuity. The salient features of this algorithm are its speed and its simplicity. It consumes less memory and CPU time. The numerical results are verified by excellent agreement with measurements.