Modelling and investigation of HTS planar resonators and filters on sapphire substrate

A semi-empirical model is developed for high-T-c superconducting (HTS) planar transmission lines on anisotropic sapphire substrates. The model takes into account the anisotropic dielectric permittivity of sapphire and its temperature dependence. A CAD tool is developed for a simulation of HTS transmission line propagation characteristics. The contribution of the HTS film surface impedance to the line propagation parameters is considered in linear and nonlinear approaches. The model is verified by the experimental investigation of a half-wavelength resonator. The model is developed for a multicoupled line structure and applied to a multi-pole filter design. Eight-pole pseudo-interdigital filters based on YBCO films on r-cut sapphires substrate with a golden ground plane have been designed, manufactured and measured. The results confirm a prospective application of YBCO films on sapphire substrates in microwave electronics.