| 摘要 |
Microwave barrier provided for identifying intruders into an area to be monitored L%. A receiver assembly 4, 5, 5a receives, from a transmitter assembly 1, 2a, 2b, 3 comprising two antennae 2a, 2b, two signals which are equal in amplitude but in phase opposition, as long as no intruder passes into the area L% separating these two assemblies; the total signal received is therefore nil. The arrival of an intruder disturbs the two received signals differently and the total signal received is no longer nil; this change in the total signal received allows an alarm to be triggered. Application, in particular, to peripheral monitoring of buildings. <IMAGE>
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