Power Performance of YBCO Thin Films on Sapphire Substrates at Microwave Frequencies

Current high temperature superconducting (HTS) components are being assessed for application in communications satellites. To justify the routine launch of satellites with cryogenic refrigerators on board, the performance gains inherent to superconducting components must be seen in both the receiving and the transmitting systems of the satellite. In order to use HTS components in transmitters, however, better high power performance is required of the superconducting materials. The power performance of YBCO superconducting thin films on Al2O3 substrates has been examined. The measurement technique used involves inputting signals of varying power into microwave transmission lines fabricated on the films. The second and third order harmonic distortion products were observed and measured. From this data, the second and third order intercept points have been calculated, and compared to YBCO on LaAlO3. The power handling capability of the YBCO films on sapphire is improved, compared to YBCO films on lanthanum aluminate.