1996 年 31 巻 12 号 p. 636-645
The recent development of high-temperature superconducting (HTS) filters for the receiver front-end of mobile telecommunication base stations and small cryocoolers is described in this paper. The merits of the HTS filters are small size, low noise and sharp skirt. One of these filters combined with a cryogenic low-noise amplifier contributes greater noise reduction to the receiver and improves the Carrier/Noise power ratio (C/N) of the transmission. The HTS filters, having high quality factors, are also effective for reducing out-of-band interference. On the other hand, cryogenic cooling is an essential and important technology for HTS filters. A reliable, low-cost, small cryocooler is required. In the USA, HTS filter systems have been field-tested using prototype equipment with small cryocoolers.