| 摘要 |
In a detection system for detecting intruders in the vicinity of a predetermined path or line defined by a distributed antenna, for example an open transmission line, an array of discrete antennas are provided alongside the distributed antenna and within a predetermined distance therefrom. The antennas are spaced apart from each other and the distributed antenna and define a plurality of detection zones. A radio frequency transmitter is connected to one of the distributed antenna and the array of discrete antennas, and a complementary receiver is connected to the other of the distributed antenna and the array of discrete antennas. A control unit controls the transmitter, receiver and array of antennas to exchange radio frequency ener gy several times via the distributed antenna and selected ones of the array of antennas and to detect perturbations caused by an intruder moving adjacent the path and adjacent a particular antenna. The antennas are scanned in sequence. Any antennas which have shown a perturbation during a previous scan will be scanned more frequently than antennas that have not previously indicated a perturbation. The antennas may be patch antennas and may be fastened to a fence, wall, trees, or a roof with the distributed antenna extending alongside, possibly buried.
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