Cross-polarization effect of radio waves propagation by forest vegetation in wireless communication systems on transport

Abstract

During the movement of various types of transport (auto, rail) in forest, radio communications in the VHF / UHF bands are sharply disturbed, which is associated with attenuation and a change in the polarization plane (cross polarization effect) of radio waves in the forest. Therefore, this paper reviews the problem of the appearance of the cross-polarization effect appearance in the through propagation of VHF/UHF radio waves in forests. The parameters of cross-polarization are analyzed and the functional dependences XPD {f, ζF, rF}, XPR {f, ζF, rF} are evaluated on the operating frequency, forest vegetation properties and the distance traveled within the forest from the transmitting antenna to the receiving antenna. Rerouted by forward and backward vegetation elements, radio signals contain many cross-polarization components that can have levels comparable to the main (useful) component. An increase in cross-polarization components can be observed in the "forward" region, which can be formed by successively decreasing the useful component, ultimately causing a significant decrease in the XPD value. As a result, the relatively high cross-polarization component can consecutively reduce the level of the useful component, while the cross-polarization effect is random, and the XPD value with fluctuating distance between the transmitting and receiving stations begins to fluctuate relative to XPD = 0. Thus, the influence of forest vegetation on the propagation conditions in VHF/UHF ranges is not only manifested in a random variation of the attenuation coefficient, but also leads to a cross-polarization effect, which ultimately causes deep fading of the radio signal at the receiving point.This work can be used in assessing the fluctuations of received signals due to the occurrence of cross-polarization during transport traffic in the forest.