Mode-Matching Analysis of Lossy SIW Devices

In this paper, we present a method for the analysis of lossy substrate-integrated waveguide structures. The analysis is achieved through the cylindrical-wave mode expansion of the field and a mode matching technique to enforce boundary conditions on the post surfaces. We introduce an approximated formulation of the previous exact procedure, valid in the microwave regime, and numerically examine a number of microwave devices using both approximated and exact analyses. These devices include filters, couplers, phase shifter, and so on. Results are presented for the scattering parameters and compared with those obtained with the commercial software in terms of accuracy and computational time.