A boundary contour mode-matching method for the rigorous analysis of cascaded arbitrarily shaped H-plane discontinuities in rectangular waveguides

A rigorous boundary contour mode-matching (BCMM) method is presented for the efficient calculation of the modal scattering matrix of cascaded, arbitrarily shaped H-plane discontinuities, junctions and/or obstacles in rectangular waveguides. For the inhomogeneous waveguide region with general contour, the field is expanded in the complete set of cylindrical wave functions. The mode-matching technique is applied at the boundary to the waveguide ports and is shown to yield quick convergence and high numerical stability. Moreover, the modal scattering matrix of the corresponding region is obtained directly. The generalized modal scattering matrix technique achieves the rigorous and flexible modeling of composed H-plane waveguide structures of arbitrary cross-section, including the higher-order mode interactions at all discontinuities, such as of inductive iris coupled filters with resonators of more general shape. The theory is verified by comparison with results obtained by other methods.<>