| 摘要 |
PURPOSE:To shut a current leaked from each antenna and to improve the sensitivity by arranging a radio wave block cylinder on the inner side of a lower- stage antenna in an on-vehicle antenna system where plural antennas acting like different antennas are arranged coaxially. CONSTITUTION:A resin-made radome 8 of a sleeve antenna 1 arranged in an upper position is inserted partly to a cylinder 38 of a monopole antenna 2 arranged in a lower position and a conductor cylinder 18 is fitted to the outer circumference of the radome 8 inserted to the cylinder and slides on the inner face of the cylinder 38 while being in electric continuity. A coaxial feeder cable 7 is penetrated through a lower end face of the cylinder 18 and a conductor disk 19 in continuity with the outer conductor of the cable 7. A current blocking cylinder consists of the cylinder 18 and the conductor disk 19 and the length of the cylinder 18 or the relation of position between the shovel top 5 of the upper stage antenna 1 and the cylinder 18 are decided to maximize the impedance between the cable 7 and the cylinder 18 at the upper end of the cylinder 18 to cut off the leakage current from the upper stage antenna 1. |
