Complex 2D discontinuities analysis using hybrid finite element method and a modified multimodal variational formulation-application to filter design

We propose a hybrid finite element method (FEM) and a modified multimodal variational formulation (MMVF) to the analysis of cascaded uniaxial complex 2D discontinuities in rectangular waveguides. The finite element method characterizes waves in the arbitrarily shaped discontinuities and the total response of the circuit is obtained by applying the modified multimodal variational formulation. The proposed hybrid method is successfully applied to the full-wave analysis of filters with great practical interest (i.e., multimode filters), thus improving CPU time and memory storage against several full-wave finite element method based computer aided design (CAD) tools.