Modeling of Cascaded Coplanar Waveguide Discontinuities by the Mode-Matching Approach

Cascaded coplanar waveguide discontinuities with transverse dimensions in the order of some micrometers are analyzed by the mode-matching and generalized scattering matrix method. This approach permits a full-wave analysis of the electromagnetic field also in the metallic regions. Compared with full-wave analysis assuming perfect conductors and a subsequent loss computation based on the surface impedance model the accuracy is considerably enhanced. The mode-matching method is revisited in the context of a network representation of discontinuities. The implications of Tellegen's general network theorem on the mode-matching method, particularly on the testing functions, are investigated. Furthermore, the mode-matching method is related to the equivalence principle applied to discontinues and to the continuity condtion of voltage and current of quasi-TEM waves in the static approximation.