CAD of folded filters and diplexers by the generalized scattering matrix of the single step discontinuity

We propose a single and rigorous procedure for the full-wave analysis of folded filters and diplexers. By following this procedure, and assuming the availability of a code producing the generalized scattering matrix (GSM) of the step discontinuity, it is shown that, in many cases, it is possible to analyze folded filters and diplexers, avoiding the development of specific routines for bends and T-junctions modelling. The analysis of the entire structure is obtained by simple matrix manipulation of the GSM and by a suitable partitioning of the device. Numerical examples validate the proposed approach.