US Patent 7423604 Waveguide horn antenna array and radar device

A conductor member contains a linear feed waveguide extending in a fixed direction and a plurality of horn antennas coupled to the feed waveguide and set at an interval of about one half of a wavelength in the extending direction of the feed waveguide. The horn antennas are formed by horns and coupling waveguides, and the coupling waveguides are set so as to partially enter the feed waveguide. When the size of the spatial coupling portion formed by the entrance is changed, the degree of coupling between the feed waveguide and each of the coupling waveguides changes.