| 摘要 |
PURPOSE:To adjust the antenna device automatically to optimum antenna length by controlling the antenna length of projection from a car body on the basis of a tuning frequency obtained from a channel selecting circuit. CONSTITUTION:The antenna length L1 of projection from the car body 10 is adjusted optionally by controlling an antenna driving motor 22. The antenna length L1 is detected by a sensor 34 and supplied to a comparator 30. The tuning frequency from the channel selecting circuit 32, on the other hand, is supplied to a channel/antenna length converter 28 to obtain the antenna length L0 suitable to the tuning frequency. The optimum antenna length 10 and antenna length L1 are compared by a comparator 30 with each other and a driving motor 26 is controlled so that the both coincide with each other. Thus, the antenna is adjusted to the optimum antenna length automatically. |
