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Shrub-blown time variability in attenuation and scattering at cellular frequencies

Caldeirinha, Rafael ; Cuinas, I. ; Gómez, P. ; Alejos, A. Alejos ; Sanchez , M.

IET Microwaves, Antennas and Propagation Vol. 4, Nº 5, pp. 526 - 542, April, 2010.

ISSN (print): 1751-8725
ISSN (online):

Journal Impact Factor: 1,187 (in )

Digital Object Identifier: 10.1049/iet-map.2009.0116

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Abstract
The interest in the electromagnetic behaviour of shrubs is growing in parallel with the extension of
radio communication networks and the need for better coverage planning tools. When a tree is present in the
vicinity of a radio link, a scattering process is likely to be induced in the propagation environment. Even
though the trunk of the tree is usually kept stationary, the wind blowing on the canopy will force its leaves to
oscillate, which induces time variability in the propagation channel. This study presents results of a
measurement campaign aimed at the characterisation of the propagation channel time variability in
vegetation media, at cellular wireless frequency bands. The results have shown that the presence of
vegetation media will contribute to the received signal level enhancement, particularly in the side- and back-
scattering regions, as opposed to the significant attenuation caused by absorption and scattering, in the
forward-scattering region. Finally, the time variability was observed to significantly decrease the dispersive
effects in vegetation media. The experimental results presented in this study provide an improvement in the
electromagnetic modelling of the scattering around isolated trees.