A new resistance measurement technique applicable to high-temperature superconducting materials at microwave frequencies

摘要

A two-gap electrically floating resonant strip was used for surface resistance measurements of the high-temperature superconductor YBa/sub 2/Cu/sub 3/O/sub 7- delta /. The method is simple, has no electrical contact, operates at various resonant frequencies, and requires only a small sample. An analysis that allows for the accurate design of the strip dimensions to produce a desired resonant frequency was used. Experimental measurements on resonant frequencies in X- and Ku-band (8-18 GHz) agree well with the calculations. The method allows one to extract the normalized surface resistance of the sample from transmission coefficient measurements at the resonant frequency. These normalized values compare favorably to the Mattis-Baredeen theory taken in the local limit. The resonant strip in waveguide should have applications in high-temperature superconductive material characterization and in the development of waveguide superconductive filters.