Mechanically tunable high-temperature superconducting microwave filter with large shift of resonant frequency

We propose a mechanically tunable superconducting microwave filter using a floating dielectric or magnetic plate which can be displaced by an actuator above the resonator for frequency tuning. We also examine the transmission and tunable characteristics of the mechanically tunable filter numerically and experimentally. The electromagnetic field simulation based on the mome nt method shows that a large shift in the resonant frequency by about 1.8 G Hz is obtained by displacement of the (La0.3Sr0.7)(Al0.65Ta0.35)O-3 [LSAT] floating dielectric plate by 0.1 mm. In the experiment, we obtained a 1.36 GHz shift from the initial center frequency of 7.05 GHz with little increas e in the insertion loss by application of an electric voltage to the electr omagnetic actuator. These results suggest that the mechanical tuning of sup erconducting microwave components is useful for optimizing frequency respon se and for the functioning of RF filter at the front end of the base statio n receiver of a software-defined radio (SDR).