| 摘要 |
PROBLEM TO BE SOLVED: To provide a sector beam antenna capable of sufficiently lowering a side lobe level and satisfying specifications to short range communication even when using an antenna cover. SOLUTION: A ground substrate 3 is provided beneath an antenna substrate 2, and on the top surface of the ground substrate 3, a plurality of antenna elements 4 for, for example, a circularly polarized wave are spaced at prescribed intervals. As the antenna element 4, for example, a circular or rectangular patch element is used. The antenna cover 5 is provided over the antenna substrate 2 at a prescribed interval d held between them to protect the antenna substrate 2, the antenna elements 4 or the like from direct rays, rain and snow. The antenna cover 5 is formed by using a dielectric, and the interval d between the the antenna cover 5 and the antenna substrate 2 is set to be in a range from 0.406λ<SB>0</SB>to 0.445λ<SB>0</SB>. COPYRIGHT: (C)2004,JPO&NCIPI
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