| 摘要 |
A low-cost, compact circular waveguide array antenna which improves an antenna reflection loss characteristic and enables an improvement in radiation characteristics, particularly radiation gain. The circular waveguide array antenna includes feeding portions which feed electromagnetic waves to one ends of circular waveguides and radiation apertures which radiate the electromagnetic waves at the opposite ends. Each circular waveguide includes a conical horn, with a diameter of a feeding side aperture at the feeding portion end being a, a diameter of the radiation aperture being d, which is larger than the diameter a of the feeding side aperture, and an opening angle being 2α. If a wavelength of a central frequency of an employed frequency band is λ, then a value of α, which is half of the opening angle 2α, is set between 0.8×Arcsin(0.1349114/(d/λ)) and 1.2×Arcsin(0.1349114/(d/λ)).
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