Superconducting transmitting / receiving bandpass filters for 5 GHz band weather Radar application

We have proposed a high-temperature superconducting (HTS) narrow-band filter for transmitter and receiver of Radar application. To realize a filter with which a narrow bandwidth and low insertion loss are compatible, resonators with high unloaded Q (Qu) value are required. Coupled microstrip line resonators with 1 time wavelength were adopted to suppress the radiation loss and achieve a high Qu value. The developed HTS filter has 8-pole quasi-elliptic function response for sharp skirt characteristic. A transmitting hybrid filter consists of superconducting resonators and conventional cavity. Novel hybrid filter structured with sandwich in superconducting resonators between two cavities realizes low power concentration in superconducting resonators. Compatibility of the high power handling capability and the sharp skirt feature is possible by this filter. As a result, power handling capability for the hybrid filter was obtained 460 W. Given these features, the high density carrier frequency assignment for next-generation Radar applications is expected to be realized by applying these filters.