Direct Determination of Multi-mode Equivalent Circuit Models for Discontinuities in Substrate Integrated Waveguide Technology

This paper presents a novel approach for the direct determination of equivalent circuit models of substrate integrated waveguide (SIW) components. This approach is based on the full-wave analysis of the SIW component by using the boundary integral-resonant mode expansion (BI-RME) method, which provides the admittance matrix of the component in the form of a pole expansion in the frequency domain. It permits to directly derive the layout of the equivalent circuit and the value of its components, avoiding any initial guess or fitting procedure. This approach is applied to the modeling of a post-loaded SIW, highlighting the possibility of obtaining parametric models, which are very suitable to direct synthesis of SIW components by using standard circuit theory techniques