FILTER SUBSYSTEMS FOR WIRELESS COMMUNICATIONS

Thin-film oxide superconductor materials and advanced processing techn iques have been used to fabricate high-performance filters for cellula r communications base stations. Quasi-elliptic bandpass and band rejec t filters were designed and realized using microstrips to approximate lumped elements, These quasi-lumped resonators have achieved unloaded Q's of more than 40,000, Precise system control allows for high operat ing temperature (97 K), using either Yttrium or Thallium high T-c comp ounds, compensating for temperature dependence, Such filters have been successfully integrated into a permanently evacuated dewar and cooled by a miniature Stirling cycle tooler. The cooler and dewar were integ rated with control electronics which run off standard cellular base st ation +27V power sources. The system consumes less than 100W in operat ion, making it one of the most efficient HTSC subsystems demonstrated to date.