Patent ID: 8134427

Claim:
A high frequency device comprising: a waveguide tube unit that transmits a high frequency signal, the waveguide tube unit having a rectangular waveguide passage through which the high frequency signal is transmitted, the waveguide passage extending in a longitudinal direction thereof and having a rectangle section cut perpendicularly to the longitudinal direction, the rectangle section consisting of short side edges and long side edges; a plate having a thickness corresponding to a length of the short side edges of the waveguide passage and having a through hole formed through the mutually-opposite surface of the plate in a direction of the thickness, the through hole having a width perpendicular to the longitudinal direction, having an inner wall and openings opened at the surfaces and the plate having electrical conductivity in a portion including the inner wall and edges of the openings; and a pair of substrates comprising first and second substrates, each substrate being made of resin and being laminated on each of the mutually-opposite surfaces of the plate and having grounding patterns electrically connected to a ground, the grounding pattern being located at a specified region of a surface of each of the substrates, the specified region positionally corresponding to the waveguide passage formed in the plate, the plate and the pair of substrates forming the waveguide tube unit, the first substrate having an area serving as an input terminal of the high frequency signal being input to the waveguide passage and the second substrate having an area serving as an output terminal of the high frequency signal being transmitted from the waveguide passage, wherein the through hole has an air passage through which the air flows to communicate with space external of the device, the air passage is arranged on at least one of the plate and at least one of the substrates; and the air passage is formed at a portion of one of the first and second substrates at which no grounding pattern is formed.