Patent ID: 6930647

Claim:
A semicircular radial antenna, comprising: a pair of semicircular waveguide plates, each having a pair of linear edge portions, an arcuate edge portion defined between the linear edge portions, the waveguide plates spaced from each other in a vertical direction; a connecting member, having a conductive face which physically and electrically connects at least a part of the linear edge portions in each waveguide plate; and a single feeder, provided between the waveguide plates so as to face the conductive face, the single feeder being spaced from the conductive face by a distance which is no greater than one fourth of a wavelength of a beam to be radiated, wherein at least one of the following requirements is satisfied: i) a position of a curvature center of the arcuate portion in one of the waveguide plates is different from that in the other one of the waveguide plates; ii) a curvature radius of the arcuate portion in one of the waveguide plates is different from that in the other one of the waveguide plates; and iii) a slanted angle of a peripheral face of the arcuate portion, which connects a top face and a bottom face of each waveguide plate, in one of the waveguide plates is different from that in the other one of the waveguide plates.