Spurious-free finite element analysis of multiaxial coplanar waveguide discontinuities

A finite element method which eliminates the spurious modes by using edge elements is used to analyse some elementary building blocks encountered in the design of coplanar waveguide (CPW) circuits. Uniaxial CPW discontinuities like a step discontinuity and a series stub are studied and their scattering matrix parameters results are compared to available published ones. Multiaxial CPW discontinuity like a right angle bend is also characterized showing the effect of the unwanted slotline mode on the transmitted power. The reliability of the results is demonstrated through the presentation of correct physical field solutions free of spurious modes for some of these discontinuities.