Realization of HTS trisection band pass filter

We report characteristics of a high-temperature superconductor (HTS) bandpass filter with the designed center frequency of 11.8 GHz. An epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) superconducting thin films were grown on a MgO substrate using the pulsed laser deposition (PLD) technique. Use of HTS films for microwave applications provides a realization of high performance planar filters with narrow passband and low insertion loss. We have designed and fabricated trisection bandpass filters with the center frequency of 11.8 GHz. In order to reduce the filter size, the filter was designed to have modified hairpin-type coupled lines. The film thicknesses were about 500 nm. Superconducting transition temperatures have shown to be about 89 K. The fractional bandwidth of the HTS filter was about 1.1% and the band rejection ratio was about 296 dB/GHz. Also the performance of superconducting bandpass filter is compared with a copper filter.