Conformal Mapping Analysis of Various Coplanar Waveguide Structures

A conformal mapping analysis of various coplanar waveguide structures is presented on silicon substrate. The analysis is based on quasi-TEM analysis which is used in formulating the electrical parameters of a transmission line. Different coplanar structure configurations are investigated. Simulation results are presented for coplanar waveguides etched on the surface of a rectangular silicon substrate. Calculated electrical parameters like line capacitance, characteristic impedance, effective dielectric constant and phase velocity and simulated results shows tapered waveguides are more suitable for tunable devices like MEMS phase shifters, varactor designs. The results shows return loss of conventional CPW designs varying from 32 dB at 1 GHz to a value of 52 dB at 40 GHz. The loss of Bow-tie and Bow-tie ground tapered configurations are above 29 dB at 1dB and above 39 dB at 32 GHz. The insertion loss obtained from simulation of the 3 coplanar waveguide designs is less than 1 dB upto 30GHz.