A full wave 3 dimensional analysis of the interaction of a low frequency electromagnetic wave with a forest

A forest made of an infinite biperiodic array of trees over a lossy ground, is illuminated by a linearly polarized electromagnetic plane wave in the range of 20 to 50 MHz. The backscattering coefficient σ₀ is obtained by means of a full wave approach, based on an integral representation of the electric field. This approach takes into account all possible interactions between each component of the medium as well as ground penetration and provides full information on the phase of the scattered field. Two models of the forest are shown: the two layers one where trees are separated and the four layers one where the canopy is replaced by an equivalent homogeneous medium. The low frequency (VHF) used here make this homogenization possible and allows one to consider trees with simple shape, the wave being unable to “see” details in the shape of a tree