CPC H01Q 1/3275 (2013.01) [H01Q 1/42 (2013.01); H01Q 15/14 (2013.01); H01Q 1/12 (2013.01)] | 5 Claims |
1. A vehicular antenna device comprising:
a directional antenna which radiates radio waves in a predetermined direction; and
a radio wave diffusion structure installed vertically above the directional antenna to reflect radio waves radiated upwards from the directional antenna in a lateral direction for omnidirectional spreading,
wherein the radio wave diffusion structure has a reciprocal cone shape with a base facing upwards and an apex facing the directional antenna, characterized in that:
the directional antenna is an array antenna formed in a square panel shape and having an upward directionality, the array antenna including a plurality of unit antenna elements arranged upwards, each of the plurality of unit antenna elements is a patch antenna,
a lateral surface of the radio wave diffusion structure is inwardly curved at a constant radius of curvature R in vertical cross section, and
a magnitude of the constant radius of curvature R satisfies Equation 1 when a magnitude of wavelength of the radiated radio waves is λ:
πλ<R<20λ [Equation 1]
where h is a vertical direction distance between an apex of the radio wave diffusion structure and the directional antenna satisfies Equation 2:
wherein d denotes a length of one side of the directional antenna, λ denotes a wavelength magnitude of radio waves radiated from the directional antenna, R denotes the constant radius of curvature of the radio wave diffusion structure, and π denotes a ratio of a circle's circumference to its diameter.
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