Simulation of an elevated coplanar waveguide using 2-D FDTD

Nonlinear transmission lines (NLTLs) are commonly used together with sampling circuits for millimeter-wave instruments. Recently, the use of an elevated coplanar waveguide (CPW) has been proposed to increase the bandwidth of sampling circuits. A full-wave analysis between 10 and 500 GHz of such an elevated CPW using 2-D FDTD is presented. The influence of the elevation heights on the capacitance and the loss behavior of the transmission line is discussed. The analysis shows that the distributed capacitance of the elevated CPW is four times lower and, the losses are at least divided by two in comparison to a normal CPW at 300 GHz.