Analytical Formulas for Conductor-Backed Connected-Ground Coplanar Waveguide

The quasi-static analysis of the conductor-backed connected-ground coplanar waveguide (CBCGCPW) with finite boundary substrate is presented. Analytical closed-form formulas for the capacitance per unit length, characteristic impedance and relative effective permittivity are given by the conformal mapping method. Compared to the coplanar waveguide (CPW) and the conductor-backed coplanar waveguide (CBCPW), the CBCGCPW has equipotential of ground planes and the electromagnetic interference is reduced greatly. The accuracy of analytical formulas is verified through comparisons between the quasi-static and full-wave analysis. Differences between the quasi-static and full-wave analysis results are less than 1% and 5% for the relative effective permittivity and the characteristic impedance, respectively. The analytical formulas can be used in CAD for CBCGCPWs.