A parallel plate resonator technique for microwave loss measurements on superconductors

A simple method for the evaluation of microwave surface loss of superconductive samples is discussed. The method allows the evaluation of small (∼1 cm×∼1 cm), flat samples over a broad range of temperatures. It can accurately characterize samples with surface resistances as low as 5 μΩ or as high as 1 mΩ at 10 GHz. In addition to high resolution, it has several advantages: sample preparation requirements are minimal; the current distribution within the sample under test is relatively uniform and can be accurately calculated; no other superconducting or normal conducting material is required for the resonator, so no additional corrections for such materials are needed; and the procedure is comparatively rapid and can be performed in the necktube of a liquid‐helium storage Dewar.