Design of TE 01d Test Probe for Measuring the Microwave Surface Resistance of HTS Thin Film
A new TE01d test probe with proper transmission factor is fabricated for the measurement of surface resistance of high temperature superconductor (HTS) thin film. Coupling holes instead of coupling loops are used in the probe for its easier machining and relatively low loss. Two 6 mm x 3 mm x 8 mm dielectric waveguides, one side of them is coated by silver, are used for coupling. The measurement result of S21 agrees well with the simulation because the size of the probe can be rigidly controlled by machine. The microwave surface resistance of four YBCO/MgO films are measured at 77 K and 12 GHz and scaled to 10 GHz according to the f 2 rule. The average surface resistance of four HTS thin films is 0.38 m, the standard devia tion and relative standard deviation of one single HTS thin film are 0.009 m and 2.4% respectively. dielectric resonator method, which is suitable for commercialization measurement, has the features of directly measuring the Rs of single piece of HTS thin film and easier calculation. This method is recommended as the supplement of HTS Rs measurement standard of China. Coupling loop was used in the device of image method before, but its shape is hard to rigorously control because usually it is handwork, furthermore, its relative high lose will decrease the Q value of the resonator, which is disadvantageous for reducing the uncertainty of the measurement. Therefore, coupling hole is used for EM transmission, and ceramic with roasting silver in it is used as an adaptor. The new structure of TE01d test probe has the advantage over the old ones since its most parts can be fabricated accurately by machine, therefore, its measure ment result of S21 agrees well with the result of simulation.