Superconducting microwave filter

In a microwave cavity filter comprised of an evacuated substantially cylindrical housing with an RF input terminal and an RF output terminal, the cavity filter preferentially coupling RF energy at at least one preferred frequency to the RF output terminal, an improvement comprising:

• at least one dielectric cylinder mounter within said evacuated substantially cylindrical housing, said dielectric cylinder having a superconducting material coating at least a portion of the exterior of said dielectric cylinder, coolant for said superconducting material being transported through only the interior of said cylinder, said dielectric cylinder and superconducting material thereon forming a superconducting resonator element within said substantially cylindrical housing coupling RF energy from the RF input terminal to the RF output terminal, said at least one superconducting resonating element establishing the resonant frequency of the filter, the filter frequency response, and RF power coupling between the RF input and the RF output terminals.