Modeling dispersion and radiation characteristics of conductor-backed CPW with finite ground width

Dispersion and radiation properties of the conductor-backed coplanar waveguide (CPW) with finite ground planes are analyzed and modeled. A frequency-domain finite-difference method using the perfectly matched layer absorbing boundary condition is used as reference. Based on these results, a closed-form description is derived and implemented into an existing quasi-static CPW model. This leads to a comprehensive and efficient CPW description accounting for all relevant effects from conductor loss to high-frequency dispersion. Additionally, design rules to avoid parasitic radiation effects are given.