| 摘要 |
The present invention has been achieved with the aim of determining the minimum number of element antennas required to suppress unnecessary sidelobe levels and obtaining a cost reduction effect. An antenna apparatus arranged in accordance with the invention has a plurality of element antennas 1 arranged on a plurality of concentric circles 2 assumed to exist on a plane and differs in radius from each other, and forms a beam in a direction inclined by theta0 at the maximum from a direction perpendicular to the plane. If the radius of the n-th concentric circle 2 from the inner side is an; the number of element antennas 1 arranged on the n-th concentric circle 2 from the inner side is Mn; and the number of waves is k, the number Mn of element antennas 1 arranged on each concentric circle 2 is determined so as to satisfy the following equation: Mn+0.81.Mn<1/3>>k.an.(1+sin theta0) Also, the element antennas 1 are arranged on each concentric circle 2 by being generally equally spaced apart from each other in the circumferential direction of the concentric circle.
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