Microwave bandpass filters contain dielectric resonators mounted in dielectric blocks, which are in turn mounted in cavities. There can be more than one dielectric resonator per cavity. Significant size reduction has been achieved over prior art filters. The filters can be operated at cryogenic temperatures...http://www.google.de/patents/US5585331?utm_source=gb-gplus-sharePatent US5585331 - Miniaturized superconducting dielectric resonator filters and method of operation thereof
