| 摘要 |
PROBLEM TO BE SOLVED: To provide an antenna that does not occupy wasteful space since resistance in movement is small and a coil spring cannot become long even when the insertion into a conductive tube in spite of the fact that an antenna shaft can be reliably retained at an arbitrary position. SOLUTION: The antenna comprises the conductive tube 3, the antenna shaft 4 that is inserted into the conductive tube 3 so that it can travel freely along a center axis (a), and a conductive coil spring 11 that is fitted on a side to be inserted to the conductive tube 3 of the antenna shaft 4. Mounting sections 8, 8' that adhere to the antenna shaft 4 and eccentricity sections 9a, 9b, and 9c are formed at the coil spring 11. The inner diameter of the eccentricity sections 9a, 9b, and 9c is made larger than the outer diameter of the antenna shaft 4. Then, in a normal state, the distance between the center axis (a) and the most separated sections of the eccentricity sections 9a, 9b, and 9c is set larger than the half of the inner diameter of the conductive tube 3.
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