Accurate Measurements of the Intrinsic Surface Impedance of Thin Films Using a Modified Two-Tone Resonator Method

We propose a modified two-tone method that could be used for sensitive measurements of the intrinsic microwave sur- face impedance of thin superconductor films and the of a low-loss dielectric. An open-gap resonator scheme is used to measure the penetration depth of thin superconductor films and extract the intrinsic of the superconductor films from its measured and . We use a very small gap of 10 between the top plate and the rest parts of the resonator. The of rutile in the low range and the dielectric constant as high as 110 are observed at temperatures below 10 K at 15.2 GHz, which en- able to measure the of the 10 mm-in-diameter YBCO films as low as at the same frequency . The discrepancy between the at 15.2 GHz and that at 8.5 GHz scaled to 15.2 GHz appears less than 2% when the relations of and are used. We describe usefulness of our measure- ment method for measuring the intrinsic microwave properties of various superconductor samples.