Electric Multimode Equivalent Network Technique for Multilayer Shielded Circuits Based on Arbitrary Rectangular Elements

The Multimode Equivalent Network (MEN) formulation has proved to be a very efficient and accurate numerical technique for the analysis of waveguide and single-layer boxed coupled lines microstrip filters. The aim of this contribution is to extend the electric zero-thickness MEN formulation to the analysis of multilayer boxed microstrip circuits that are based on arbitrary rectangular elements and include ports in the transverse plane. For this purpose, the MEN approach is used to model each metal interface in the multilayer stack with the appropriate equivalent network. The equivalent networks are then conveniently cascaded to obtain the final equivalent network that characterizes the complete circuit. The theory developed is then used to analyze a trisection filter composed of two metallization levels. The simulation results are shown to be in good agreement with measurements thereby fully validating the multilayer electric MEN formulation.