Tokarev Nikolay Nikolaevich, Candidate of engineering sciences, chief specialist in radio-wave detectors, division №134, Research and Design Institute of Radio-Electronic Engineering – branch of JSC “FSPC “PC “Start” named after M. V. Protsenko” (building 1, 1 Mira avenue, Zarechny, Penza region, Russia), E-mail: email@example.com
Background. Forests provide the covert approach of intruders to vital protected facilities. Therefore, the detection of people and equipment in the forest is an urgent task. To fulfill this, it is necessary to use radio-wave detectors (RWD) of the meter wavelength range. Interference to RWD is reflections from tree crowns swaying in the wind. The article analyzes this type of interference.
Materials and methods. It is used a tree model in the form of a pinched cantilever cone beam with application of wind force to its top. Using this model, the crown deviations in horizontal and vertical directions are estimated when exposed to wind. The interference model is determined as a result of the direct beam interference and the beam reflected by the oscillating diffuse surface of an array of tree crowns.
Results. Two cases of detector location are considered - inside the forest and at the edge of the forest. They differ in the direction of oscillation of the reflecting surface. In the forest, this surface is horizontal and it oscillates in the vertical direction. At the edge of the forest, this surface is vertical and oscillates in the horizontal direction. The amplitude of oscillations in the horizontal direction is greater than in the vertical. It has been established that the amplitude of interference is mainly determined not by the amount of deviation of the reflecting surface, but by its reflection coefficient, which depends on the density of tree crowns, and the angle of incidence.
Conclusions. In the RWD operating frequency range the magnitude of the interference is much lower than the signals generated by an intruder (a person) and does not prevent his/her detection.
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