Wideband analysis of E-plane metal insert filters by the "Boundary Integral - resonant mode expansion method"

A very fast and accurate method for the analysis of metal insert waveguide filters is described. The algorithm yields in a single step the poles and the residues involved in an approximate wideband representation of the Y-parameters. The key point is the determination of the first few resonant modes of the cavity obtained by closing the ports of the filter by conducting walls. The efficiency of the method depends on the possibility of determining these modes by the solution of an integro-differential eigenvalue equation, whose discretization results in a small-size linear matrix eigenvalue equation. Some results demonstrate the possibility of determining all the frequency response in CPU times of the order of 1 sec, using an ordinary workstation.