Uniaxial discontinuities analysis by a new multimodal variational method - Application to filter design

A new mulitimodal varational formulation (NMVF) is presented for the characterization of cascaded discontinuities in microwave components by using a formal admittance operator of the complete structure. The admittance operator is constructed by using all higher-order modes in intermediate waveguides, so that the convergence study versus the number of modes will no longer be needed, contrary to classical modal decomposition methods. This formulation will theoretically lead to increased accuracy for the overall S parameters. To validate this new approach, a step-discontinuity is analyzed and an evanescent mode bandpass filter is designed. (C) 2006 Wiley Periodicals, Inc.