Design and development of low loss microstrip band pass filters by using YBCO- high temperature superconducting thin film

To demonstrate the suitability of HTS filters we chose a four pole chebyshev band pass filter with 80 MHz band width, insertion loss of 0.5dB at 4035 MHz center frequency on LaAlO
₃
single crystal with YBCO HTS thin film. The filter was designed with four-pole quarter wave parallel-coupled line. To check the validity of filter design, two filters were fabricated using gold thin films of 0.5 microns thickness on 0.5mm thick LaAlO
₃
. The filter showed an insertion loss of 8.5 dB at the pass band at room temperature and 3.5 dB at 77degK.