Improvement of accuracy in measurements of the surface resistance of superconductors using dielectric resonators

Two techniques to minimize the influence of parasitic losses on surface res istance measurements of superconductors employing dielectric resonators hav e been described, The first method optimizes the sapphire resonator aspect ratio to minimize the parasitic losses for given superconductor sample dime nsions and measurement frequency. The second utilizes a reference resonator with a perfect conductor plane to cancel out the influence of parasitic lo sses by measurements of the resonant frequencies and Q-factors of two reson ators. The second technique is recommended when materials having noticeable dielectric losses are used to construct dielectric resonators.