Wind effect on the scattering from vegetation at cellular phone frequencies

The presence of vegetation in the radio channel could affect the coverage areas of cellular mobile phone systems. The different components of a tree have influence in the performance of the radio system. Whereas the trunk is commonly in a fixed and stable location, the leaves could be in continuous movement forced by the wind. This time variation, which can be correlated with the wind speed and direction, could strongly modify the attenuation and scattering effects of the trees on the radio channel performance. The present paper contains the results of a measurement campaign of scattering and attenuation effects of isolated trees, under the action of artificial wind of different controlled speeds and directions. Both long-term and short-term results are presented. They show that the median effect of the presence of the tree is the induction of higher attenuation in the shadow areas and a new distribution of the scattering pattern all around the specimen. Whereas, the wind on the leaves forces their movement and an increment in the time variation around the median received power values.