| 摘要 |
An antenna coupler for coupling a portable radio to an auxiliary antenna to provide transmission and reception through the auxiliary antenna. The antenna coupler includes an outer tubular conductor and an inner tubular conductor coaxially disposed within the outer tubular conductor. An end cover having an antenna opening is secured to one end of the tubular conductors. The radio and auxiliary antenna are placed in a coupled position by inserting the on-board antenna into the inner tubular conductor. The coupled, on-board antenna and inner tubular conductor form a close-coupled transmission line with the antenna functioning as the central conductor and the inner tubular conductor functioning as an outer conductor of the transmission line. The inner tubular conductor is conductively connected to an impedance matching circuit and RF connector for providing impedance matching and interconnection with the auxiliary antenna. In addition, the outer tubular conductor is grounded to the radio collar to provide a common ground, and functions as the outer ground or shield for the close-coupled transmission line.
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