Analysis of Coplanar Waveguide With a Bottom Ground Aperture

Analytical expressions of characteristic impedance and effective permittivity of a coplanar waveguide (CPW) with a ground aperture on the bottom layer have been obtained with conformal mapping techniques. The contribution due to leakage field through the aperture is carefully treated in this analysis. The analytical expression of the characteristic impedance is shown to be within 4.1% as compared with the EM simulation results.