Characterisation of discontinuity effects in triple ridge waveguides using 90° and 180° unit elements

The discontinuity effect at a step between any two waveguides is an important aspect in the design of impedance steps and filter structures. The purpose of this paper is to characterise the effect between a regular rectangular waveguide and a triple ridge waveguide propagating its dominant mode. One method of achieving this is to employ a 180° UE in conjunction with a calculation of the characteristic impedance and wavelength of the ridge waveguide. Another method is to have recourse to its odd-mode eigen-network. Both procedures are employed in order to obtain data on such a discontinuity. Results are in accord with separate calculations using a commercial finite element (FE) solver.