| 摘要 |
PURPOSE:To attachably/detachably obtain an antenna system whose directivity fre quency characteristic is able to be decreased by assembling a cone taper and a directivity shaping concave lens to a radome incorporatedly and adopting a structure to be screwed to a circular waveguide of a horn antenna main body. CONSTITUTION:Denoting the mechanical size being a difference of path length of an aperture face B without a concave lens 3c as delta and the size of the concave lens 3c as (d), then the phase phi at the aperture ridge face B is retarded by equation I only (inverse of lambdag represents an integration mean value of a guide wavelength). In adding the concave lens 3c to the aperture, a new phase error DELTAphi (equation II) is added when a radio wave is transmitted therethrough, where lambda is a free space wavelength and epsilonv is a specific dielectric constant of the type of material of the concave lens. In mounting the concave lens 3c, the phase lag phi at the aperture ridge end face B with respect to the center is expressed as equations I+II=equation III, and the phase error is further increased with high frequencies in comparison with the equation I. The beam width is wider when the phase error is increased in the directivity of the horn antenna and the frequency characteristic value as to the directivity is decreased before the mounting in mounting the concave lens 3c.
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