High Tc superconductor microwave resonators and filters

Abstract

Abstract An approach is expected for an evolutionary advancements of high Tc superconducting(HTS) microwave devices to meet requirements at first for ultra-multichannel communication for use on earth and in space presented, next for a growth path to achieve the potential of mobile telecommunications using satellites in space for use on earth, and then for space infrastructure evolution, including the solar power satellite which is to convert solar energy in space for use on earth by beamed microwave power transmission. We have developed superconducting 13.3GHz microstrip resonators and filters, which use Au as ground planes. Thin films of high Tc superconductor(HTS) YBa2Cu3O7−δ(YBCO) deposited by ArF pulsed laser ablation on MgO have been lithographically patterned to form straight line resonator and three-pole Tchebyscheff bandpass filter structures, adjusting their central frequencies by a focused KrF puled laser step-by-step cutting and ion beam milling at grazing angles of the c-axis-oriented YBCO film. The structure of resonator and filter is the best candidate for hybrid superconducting-semiconducting microwave circuits and also for a characterization tool to precisely measure HTS film quality. In order to investigate the realization of thin-film microstrip(TFMS) using HTS film growth technique, we have measured the microwave power dependence of the YBCO resonator and filter up to 20dBm at 13.3GHz. Then, the unloaded Q value and the insertion loss were obtained to exceed those of the gold(Au) resonator and filter below 77K over range −20dBm to +20dBm, respectively. The greatly reduced individual filter sizes and weights may offset the cost and inconvenience of cooling the entire filter banks.