Intrusion detection barrier

DETAILED DESCRIPTION According to the present invention, there is provided an intrusion detector barrier comprising: a coiled wire fence deployable over the ground or over another fence; a sensor wire tensioned between a pair of wire-supporting posts anchored in the ground; an intrusion detector connected to the sensor wire to sense any change in tension thereof; and coupling members coupling the sensor wire to spaced points of the coiled wire fence.
Preferably, each of the coupling members permits free movement of the sensor wire with respect to the coiled wire fence in the direction of the longitudinal axis of the sensor wire, but restrains movement of the sensor wire with respect to the coiled wire fence in the direction transversely to the axis of the sensor wire.
Such a system can be produced at relatively low cost, and can be deployed in a quick and convenient manner wherever the need arises.
Moreover, by providing coupling members which permit free movement of the sensor wire in the longitudinal direction but restrains movement in the transverse direction, the sensor wire can be tensioned in long spans between widely-spaced wire supporting posts anchored in the ground, e.
g.
, in spans of several hundred meters.
This enables a minimum number of wire-supporting posts to be used, thereby further reducing the cost and simplifying the deployment of the barrier.
Such an arrangement also reduces the sensitivity of the system to gradual forces, such as may be produced by the wind or the settling of the ground, thereby decreasing the number of false alarms.
While it is preferred to use coupling members permitting free longitudinal movement but restrained transverse movement of the sensor wire with respect to the coiled wire fence, an arrangement may be used wherein each of the coupling members fixedly attaches the respective point of the sensor wire to a part of the coiled wire fence.
Such an arrangement provides greater sensitivity to detecting all disturbances, and also prevents the possibility of cutting the coiled wire fence and sliding it along the tensioned sensor wire in order to bypass the system