The rigorous CAD of aperture-coupled T-junction bandstop-filters, E-plane circuit elliptic-function filters, and diplexers

The rigorous computer-aided design (CAD) of waveguide bandstop filters, elliptic-function E-plane integrated circuit filters with additional bandstop cavities, and high-return-loss E-plane T-junction diplexers with iris matching elements is introduced. Based on the general rectangular waveguide T-junction key building block modal S-matrix, the design takes into account both the finite thickness of all coupling elements and the higher order mode interaction at all step discontinuities. The theory is verified by measurements.<>