Microwave barrier
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GENERAL OPERATING PRINCIPLES
The transmitter unit and receiver unit are placed at opposite ends of the area to be protected. The
transmitter unit emits electromagnetic waves in the direction of the receiver unit. The receiver
unit receives these waves, converts them into an electric signal, and analyzes this signal.
An intruder who penetrates the detection zone – either at full height or bent down – triggers the
modulation of the signal received by the receiver unit. The depth of the modulation and the form
of the signal depend on the size and mass of the intruder, the place where the area is penetrated,
the relief of the area and the speed of the intruder’s movement. The detector in turn signals the
generation of an alarm by opening the output contacts of the terminal control relay.
A special feature of the design, in conformance with the intended functional properties of the
detector, is the very narrow detection zone in the direction of the antennas, due to its ‘K’-band (24
GHz) operating frequency range. Use of this comparatively high operating frequency band not only
contributes to the narrow width of the detection zone, but also ensures higher sensitivity to moving objects
in the direct vicinity of the detection zone axis.
A sample view of the detection zone profile of a 984 ft. (300 m)-long segment is shown in
Figure 1
.
Figure 1
– Sample view of the detection zone profile
The detector has two modes for the determination of a proper detection threshold level: ‘auto’
and manual. In ‘auto’ mode, the processor determines the optimal threshold level for the
detection of intruders penetrating the detection zone on a ground surface. In manual mode, the
optimal detection threshold level is explicitly specified by the operator. As a rule, the need for
manual adjustment arises in the event of a significant operational variation from the routine
operating conditions specified in this manual.
It should be noted that, in ‘auto’ mode, the optimal detection threshold level is determined in dB
in relation to the average strength of the radio signal received. The detector automatically adapts
to gradual changes in the received radio signal’s average strength resulting from slow changes in
weather conditions.
