Efficient CAD of E-plane steps in rectangular waveguide

The classical problem of coupled E-plane step discontinuities is reconsidered. It is shown that including the edge condition it is possible to find a basis that, with only one or at most two terms, represents, to a high degree of precision, the field aperture. The frequency dependence of the problem is considered and simplified by assuming the equivalent lumped representation of the modal admittances. As a result a simple, broadband, equivalent circuit that provides an efficient tool for CAD analysis of cascaded discontinuities is obtained.<>