| 摘要 |
PROBLEM TO BE SOLVED: To provide a semicircular radial antenna which can enhance a gain. SOLUTION: A semi-circular upper waveguide plate and a lower waveguide plate 3 are disposed opposite to each other at a predetermined interval, and the base (straight end part) is short-circuited by a short-circuit wall 4 for constituting a semi-circular radial waveguide path 5 between the upper waveguide plate and lower waveguide plate 3. Further, U-shaped groove formation plates 6, 7 are mounted along the outer margin at a predetermined interval on the upper surface of an upper waveguide plate 2 and on the lower surface of the lower waveguide plate 3, to form grooves 8, 9. Namely, the grooves 8, 9 are formed on the front end sides of the upper waveguide plates 2, 3. A feed part 11 is provided at a center position on a side of the short-circuit wall 4 in the lower waveguide plate 3. As described, the grooves 8, 9 are formed on the front end sides of the upper waveguide plates 2, 3, thereby decreasing unwanted radiation to the antenna rearward region and gain is enhanced.
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