Tunable High Temperature Superconducting Filters

There is a significant market for tunable filters with potentially large defense and commercial applications. The role of high temperature superconducting (HTS) materials for the fabrication of high performance microwave devices is getting increased recognition. The realization of tunable high performance HTS microwave devices could open up potential markets in the satellite and mobile communications field. Tunable HTS devices, either for changing the operating frequency of a device or for introducing a desired delay, will constitute a class of desirable devices for the communications industry. In Phase I, we propose a feasibility study for the construction of a tunable filter utilizing two approaches. The first approach will utilize a hetero-structure consisting of a superconductor filter in conjunction with a voltage tunable dielectric layer. The second approach will utilize a voltage tunable diode capacitor in conjunction with a superconducting resonator. In both approaches the challenge will be to preserve the high Q values obtained using HTS resonators and yet achieve a high degree of tunability for reasonable voltage levels. The preferred approach will be pursued in the Phase II of the proposal to develop advanced tunable filters.