Patent ID: 8111158

Claim:
An intrusion detection system comprising: an intrusion detection device; and a pair of separated leaky transmission paths including a leaky transmission path of a sending side, connected to the intrusion detection device, for emitting a leaky electric wave supplied by the intrusion detection device and a leaky transmission path of a receiving side for receiving the leaky electric wave emitted from the leaky transmission path of the sending side, wherein the intrusion detection device detects an intrusion between the separated leaky transmission paths and its location from a variation of the leaky electric wave received in the leaky transmission path of the receiving side and has a function unit for varying the frequency of the received analog signal input from the leaky transmission path of the receiving side to the intrusion detection device, and wherein an anti-disturbing wave function unit for removing or reducing a disturbing wave intruding into the leaky transmission path of the receiving side is provided, in the intrusion detection device, so that the intrusion detection device determines the intrusion and its location using the leaky electric wave processed by the anti-disturbing wave function unit.