Modeling of high-Tc superconducting coupled microstrip lines on sapphire substrate

Closed form models are proposed for propagation parameters of high-TC superconducting (HTS) coupled microstrip lines taking into account anisotropy of dielectric properties of sapphire substrate and a non-homogeneous current distribution in the coupled strips and in the ground plane for the even and odd modes. The models were verified by a comparison with full-wave analysis results and by an experimental investigation of a coupled lines HTS resonator.