Precision and accuracy of surface resistance measurement with the dielectric resonator method

The surface resistance of high-T/sub c/ superconducting films at microwave frequencies was measured by the dielectric resonator method using two sapphire rods. The dielectric resonator method is appropriate for the standard measurement of surface resistance at microwave frequencies. We focused on several sources of error in this method, i.e., temperature inhomogeneity in the resonator, asymmetry in coupling and the parasitic coupling effect, and discussed the precision and accuracy of the measurements. It was found that parasitic coupling is the main source of measurement error and we proposed several types of resonators to eliminate the parasitic coupling. These results were reflected in the working draft of the International Electrotechnical Commission Technical Committee 90(IEC/TC90).