Patent ID: 8599090

Claim:
A waveguide slot array antenna apparatus, comprising a waveguide slot array antenna formed of a rectangular antenna waveguide which has a rectangular section orthogonal to a tube axis, wherein: the rectangular antenna waveguide has one end side thereof in a tube axial direction serving as a feeding port and another end side short-circuited; the antenna waveguide has a plurality of slender rectangular opening portions for radiating or receiving an electromagnetic wave arranged at intervals of about λg/2 (λg is an intra-tube wavelength) along the tube axis on a first wide plane of a pair of wide planes that are parallel to the tube axis; the plurality of slender rectangular opening portions each have the same predetermined angle with respect to a center line parallel to the tube axis of the first wide plane; the slender rectangular opening portions adjacent to one another are alternately arranged at opposite positions with respect to the center line; the slender rectangular opening portions located on one side with respect to the center line of the first wide plane each have a length longer than about λf/2 (λf is a free space wavelength), and the slender rectangular opening portions located on another side each have a length shorter than about λf/2; at least one waveguide slot array antenna including an antenna joint waveguide configured so that two of the rectangular antenna waveguides are joined at positions of respective feeding points in opposite directions so as to align the respective tube axes and having both ends thereof short-circuited; and one feeding waveguide disposed on a second wide plane side of the pair of wide planes of the waveguide slot array antenna, wherein: the feeding waveguide is coupled with the second wide plane of the antenna joint waveguide via a coupling portion, wherein the coupling portion comprises a coupling opening portion formed in each of the waveguide slot array antenna and the feeding waveguide, or a coupling opening portion formed in the waveguide slot array antenna and a coupling tube formed in the feeding waveguide and coupled with the coupling opening portion of the waveguide slot array antenna.