Extension of the BI-RME method to the analysis of piecewise-homogeneous waveguide components including arbitrarily shaped building blocks

This paper presents an enhanced technique for the numerical modeling of waveguide components. The component is segmented into building blocks, and the Boundary Integral-Resonant Mode Expansion (BI-RME) method is used for the calculation of the generalized admittance matrix (GAM) of each building block. To preserve the generality of the method, RWG basis functions are defined on the surface of each building block to represent the unknown electric and magnetic surface currents, and each entry of the GAM relates a pair of basis functions. The theory previously developed for the analysis of boxed building blocks is extended to arbitrarily shaped blocks. An integral equation is formulated by imposing appropriate boundary conditions to the electromagnetic field. Thanks to the particular BI-RME representation of the kernel, the integral equation is converted into a linear eigenvalue problem, whose solution lead to the determination of the GAM. By cascading the GAMs of the building blocks, the frequency response of the whole component is finally obtained. The theory of the method is outlined in this paper, and numerical examples demonstrate the capabilities of the proposed algorithm.