Analysis of discontinuities in inhomogeneously doped slow-wave coplanar waveguide using the FDTLM method

摘要

This paper present a numerical investigation of discontinuities between coplanar waveguide (CPW) and slow-wave MIS CPW with inhomogeneous doping regions. The frequency-domain TLM (FDTLM) method is applied to calculate the scattering parameters for the abrupt transition from a normal CPW on insulating substrate to an MIS CPW on doped substrate. The effect of various lateral widths of the doping region on the S-parameters of such a transition is investigated. It is found that limiting the lateral extend of the doping region to the area below the slots and the center conductor not only provides a high slow-wave factor at low losses but also provides much better S-parameters compared to the case where the doping is extended over the whole transmission line cross-section.