Microwave multipole lowpass and bandpass filters fabricated by high-T/sub c/ superconducting thin films

The design, fabrication, and measurement of 7-pole microstrip lowpass filters and 4-pole parallel coupled-line bandpass filters using superconducting YBa/sub 2/Cu/sub 3/O/sub 7-x/ epitaxial thin films are presented. The YBa/sub 2/Cu/sub 3/O/sub 7-x/ films were grown in situ at 770/spl deg/C and 200 mTorr oxygen partial pressure in a pulsed laser deposition system. The 7-pole microstrip-line lowpass filter and 4-pole parallel coupled-line bandpass filter patterned on the laser ablated YBCO films with dimension of 20 cm/spl times/10 cm/spl times/0.5 mmt were generated using photolithographic and wet etching processes. The complete devices packaged in a 3-component type brass test-fixture were characterized. The results showed the center frequency of 11.2 GHz with 6% bandwith and less than 1 dB insertion loss(IL) for the case of bandpass filters below 77 K.<>