Accurate Measurements of Surface Resistance of HTS Films Using a Novel Transmission Mode Q-Factor Technique

Abstract

Microwave characterization of HTS films, using typically a sapphire dielectric resonator can only be as accurate as the Q0-factor and fres measurements. A novel Transmission Mode Q-Factor (TMQF) technique has been used for accurate measurements of surface resistance of YBa2Cu3O7 films, with errors lower than 1%. The method allows for accurate determination of QL, β1, and β2 based on novel equations and a multi-frequency circle-fitting technique applied to S21, S11, and S22 measured around the resonance. Parasitic effects introduced by real measurement systems, namely, noise, crosstalk, coupling loss, coupling reactance, and electrical delay due to uncalibrated transmission lines are compensated for in the new method. Range of unloaded Q0-factors that can be measured with the TMQF technique is assessed to be from 100 to 10 million at the GHz range of frequencies.