| 摘要 |
PURPOSE:To improve the impedance matching by selecting the length of an inner conductor containing an antenna element as a specific value and selecting the length of a cylindrical outer conductor insulated electrically from the inner conductor as the length of the inner conductor. CONSTITUTION:The antenna element 13 is contained in a cylinder fitted to a single body of an automobile while being decreased telescopically and used while being expanded upward from the cylinder. A cylindrical inner conductor 16 is formed to the inner circumferential face of the cylinder 14 and a cylindrical outer conductor 17 insulated electrically from the inner conductor is formed to the cylindrical outer circumferential face. The outer conductor 17 is connected to a car body 12 electrically and the length l1 of the inner conductor 16 is selected as expressed in equation and the length l2 of the outer conductor is selected to be the length l1 of the inner conductor or over, then the impedance matching between the antenna element and the cable is improved.
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