A practical microwave subsystem of HTS filter integrated with coaxial pulse tube refrigerator

The pulse tube refrigerator is a competitive new technology for cooling HTS microwave devices because it involves no moving parts at low temperature. A new Chebyshev type 8-pole band-pass filter with bandwidth about 1GHz at 5 .6 GHz was designed and fabricated on a 20x20x0.5 mm LaAlO3 substrate. Inte grated with a coaxial pulse tube refrigerator, the filter shows satisfactor y performance with low insertion loss ((less than 0.6dB) and high out band rejection (better than 60 dB), which demonstrated successfully the potentia l application of the integrated device and the refrigerator as a practical HTS sub-system.