Patent ID: 7304554

Claim:
A filter, comprising: a body for forming a U-shaped waveguide groove thereon, said U-shaped waveguide groove having two openings on one side of the body and a plurality of inductive resonant windows along a longitudinal direction of the waveguide groove at a predetermined interval; and a cover placed on a top surface of said body so as to cover said waveguide groove; wherein said plurality of inductive resonant windows are provided in such a manner that a cavity, which is enclosed by two of said plurality of inductive resonant windows being adjacent, said body and said cover, resonates at a predetermined frequency and passes a electromagnetic wave in a predetermined frequency band; wherein one opening of said two openings is an input terminal for inputting the electromagnetic wave and the other opening of said two openings is an output terminal for outputting the electromagnetic wave; and wherein said waveguide groove forms a waveguide in such a manner that a wider surface of the waveguide is along a depth direction of the groove, a narrower surface of the waveguide is provided by said cover, and two wider surfaces extend from said input terminal and output terminal.