Surface Resistance Measurements of HTS Films by Means of Sapphire Dielectric Resonators

We used sapphire dielectric resonator technique with copper cylindrical shield and two endplates replaced by HTS layers for very accurate surface resistance measurements of laser-ablated YBCO films, The resonant system using the TE011 mode has resonant frequency of about 18.1 GHz and parasitic losses Omega factor of about 120,000. It allows 10 mm X 10 mm samples to be measured with sensitivity of +/- 30 mu Omega. Individual samples can be measured with somewhat lower accuracy. Using larger HTS samples, one can reduce parasitic losses of the system to an unsignificant level. The exact formulas presented further below for the resonant system allow for avoiding calibration procedures during the evaluation of the surface resistance value.