Patent ID: 7183874

Claim:
A casing contained filter comprising: a filter formed on a dielectric substrate; and a casing in which the filter is contained, the filter comprising at least one resonator formed on the dielectric substrate and a first and a second input/output terminal section formed on the dielectric substrate and coupled with the resonator, the resonator comprising a signal conductor formed on one surface of the dielectric substrate and a ground conductor formed on at least one of said one surface and the opposite surface of the dielectric substrate, the casing comprising a square tubular body of copper plate which is plated with gold, and a high temperature superconductor such as lanthanum-, yttrium-, bismuth- or thallium-superconductor is deposited as a film on a substrate of a metal oxide material such as MgO, SrTiO 3 , LaGaO 3 , LaAlO 3 to provide a superconductor filmed substrate which is applied to the internal wall of the square tubular body.