CAD model for coplanar waveguide synthesis

Accurate closed-form synthesis formulas for coplanar waveguides are presented for CAD applications, which are approximated in terms of ordinary functions. These formulas are derived from function approximation and curve-fitting correction of quasi-static numerical results. Comprehensive comparisons have been made by using results from the quasi-static analysis, the rigorous full-wave analysis, and the experiment available in the literature. Accuracy is found to be better than 1.5 percent for the practical range. The application range of frequency is within the limits well known for quasi-static TEM approximation and can be applied up to 20 GHz.