Patent ID: 8564490

Claim:
An antenna device, comprising: a waveguide antenna having wall surfaces and for emitting a radio wave in a direction substantially perpendicular to an emission face that is one of wall surfaces of the waveguide antenna extending in an elongated direction of the waveguide antenna; a plate-shape two-dimensional opening slots for beam formation formed in the waveguide antenna on the emission face side; a power feed waveguide module arranged in the rear face of the waveguide antenna opposite from the emission face and for supplying electric power to the waveguide antenna; and a cylindrical radome having a substantially circular cross-section of a diameter that is substantially equal to a length of the emission face in a direction perpendicular to the elongated direction so that the waveguide antenna is contained in the radome so as to be arranged at substantially the center of the radome, and including an outer wall of a substantially semi-circular side cross-section on the emission face side; a first inner wall, arranged inside of the outer wall and formed up to the prescribed position with a constant gap from the outer wall, and a second inner wall extending from the prescribed position as one end thereof and having a cross-section parallel to a direction from the substantially midpoint toward the center of the substantially semi-circular shape.