Figure 5-8. Bistatic Microwave Sensor Operation

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UFC 4-021-02NF

27 September 2006

change 1, 23 October 2006

5-4.3.3.2 The detection zone should be graded to within three inches to detect crawling

intruders.

5-4.3.3.3 Grass should be kept cut to less than three inches. A gravel surface prepared

for water drainage is better than a grass surface. Since a typical microwave pattern is

ten feet by ten feet, a twenty-foot wide gravel bed works well.

5-4.3.3.4 Avoid water puddles. The wave action of wind on water can cause nuisance

alarms.

5-4.3.3.5 For high security applications, consider use of stacked sensors (one sensor

on top of another), with the lower frequency (wider/broader pattern) on top and the

higher frequency (more focused pattern) to detect crawling intruders on the bottom.

5-4.3.3.6 Do not place sensors too close to perimeter fences. Wind action on the fence

fabric can cause false alarms.

Figure 5-8. Bistatic Microwave Sensor Operation