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Yoshiki UENO Nobuyoshi SAKAKIBARA Teruaki YAMADA Mitsunari OKAZAKI Masayuki AOKI
High-temperature superconductor (HTS) receiving filter subsystem for mobile telecommunication base station has been developed. An 11-pole HTS filter using YBa2Cu3O7-δ (YBCO) thin films and a low noise amplifier were cooled to 70 K by a small cryocooler. Total noise figure of this subsystem was measured to be 0.5 dB. Furthermore the effect of using the subsystem in the receiver front-end of Code Division Multiple Access (CDMA) cellular base station was investigated. The transmitting power reduction of handy terminal was estimated to be about 35%.
Yoshiki UENO Kenshi SAITO Nobuyoshi SAKAKIBARA Mitsunari OKAZAKI Masayuki AOKI
Large-area high-temperature superconducting films and damage-free processing techniques have been developed to fabricate low insertion loss and sharp skirt filters for mobile telecommunication. An off-axis-type dc sputtering method was employed to deposit Y-Ba-Cu-O films on both sides of the substrate. The surface resistance of the films was about 0. 35 mΩ(at 70 K and 10 GHz). An 11-pole bandpass receiving filter for the IS-95 telecommunication system was designed and fabricated using 60 mm 50 mm YBCO films on a 0. 5-mm-thick MgO substrate. The passband insertion loss at 70 K was about 0. 1 dB with 0. 1 dB ripple. The third-order intercept point of the filter was 49. 5 dBm. We have assembled the filter and a low-noise amplifier in a dewar with a cryocooler. Ultralow-noise performance (noise figure: 0. 5 dB at 70 K) was presented by the cryogenic filter subsystem.