High Temperature Superconducting Microwave Filters for Applications in Mobile Communication, Satellite Receiver and Wind-Profile Radar

Three types of high performance high temperature superconducting (HTS) filters for different applications are introduced. The HTS filter for 3G mobile base station, which is constructed by multi-loop resonators, showed ultra selectivity with extremely small fractional bandwidth (narrower than 0.23%), extremely steep skirt slope (140- 220 dB/MHz) and excellent out-of-band rejections. The integrated bandpass and bandstop HTS filters for satellite receiver made by YBCO and TBCCO thin films achieved very small return loss (les -22.5 dB) and extremely high out-of-band rejection at certain frequency bands (> 110 dB) simultaneously and showed satisfactory results in the space qualification mechanical tests. Field tests of the wind-profile radar exhibited that with HTS subsystem an increase of 3.7 dB in sensitivity and an improvement of 48.4 dB in anti-interference ability of the radar were attained so that when conventional radar failed to detect the speed and direction of the wind above 2000 meters of the radar due to interference, the HTS radar can produce perfect wind spectrums and profiles.