A simplifid analysis of coplanar waveguide coupler by using conformal mapping transformations

A simplified study for microstrip coplanar waveguide coupler is presented. In this study a new formulas for even and odd mode capacitance in multi-layers structure have been proposed. The proposed formulas are derived based on the conformal mapping method. In this paper the effect of multi-layers substrate with different dielectric constants on the propagation characteristics of cpw coupler has been presented. We have compared the results given by spectral domain method. The comparison indicating that the proposed formulas are accurate, and efficient for determing the propagation characteristics in multi-layers microstrip structure.