| 摘要 |
PURPOSE:To obtain a small-sized antenna system having a wide band characteristic by detecting effectively a current induced in a car body due to a broadcast wave and transmitting the result of detection to an on-vehicle receiver. CONSTITUTION:A high frequency pickup 38 is provided to a special position of a rear window frame 34. A loop antenna 42 is included in the inside of the pickup 38 and a magnetic flux induced from a high frequency surface current flowing in the inside of a metallic case 40 and at the edge of the frame 34 is measured by the antenna 42. A circuit section 58 connected to the antenna 42 is incorporated in the case 40. A varactor diode 70 is is provided in the circuit section 58 and adjusts the resonance frequency of the pickup optionally, the capacitance of said diode 70 is selected by using the tuning frequency of the on-vehicle receiver to control that the tuning frequency of the receiver and the resonance frequency of the pickup 38 are made coincident. The mounting position of the pickup 38 is selected at a position where the largest car body current induced by a ratio wave is given. |
