Electromagnetic backscattering from a sparse distribution of lossy dielectric scatterers

Abstract

Electromagnetic backscattering from a sparse distribution of lossy dielectric particles having random orientation and position is studied. The paper begins by using the Foldy approximation to find an equation for the mean field. From this equation, an effective permittivity for the scattering medium is obtained. The correlation of the scattered field is found by employing the distorted Born approximation, i.e., particles embedded in the effective medium are assumed to be single scatterers. The above method is then used to find the backscattering coefficients from a leaf canopy. The leaf canopy is modeled by a half space of dielectric discs that are small in comparison to a wavelength. Numerical results show that the depolarized cross section is a sensitive function of leaf inclination angle statistics.

Radio Propagation in Rural Residential Areas with Vegetation

“…The deviation between the calculated and measured values according to (26)- (28) does not exceeds 6-7 dB. On the other hand results of calculations made by use of the model that does not take diffraction into account give much larger deviations from the experimental data, of 8-10 dB (for points [20][21][22] and of 15-25 dB (for points 14 and 8). The same result can be observed at all sites, as presented in Fig.…”

“…Later, during the seventies, vegetation and foliage losses have been reported [11][12][13] at frequencies up to 10 GHz but for relatively few paths. As follows from literature [14][15][16][17][18][19][20][21][22][23][24][25][26], trees have both absorbing effect (caused by scattering from foliage) and diffraction effect (caused by a lateral wave created by the top of the tree layer), mainly for propagation over the trees. Up until today, there is not any satisfactory analytical or statistical propagation model, which could explain both building and vegetation effects.…”

“…Let us now analyze variations of the total path loss according to (31) for the model of single scattering and diffraction which is stricter than other model of multiple scattering without diffraction describes situation in the mixed environment with vegetation and, as follows from formulas (20) and (21), more sensitive to terrain parameters variations. In this case we get, after some straightforward derivations: …”

“…Tamir's deterministic model of dielectric layer is valid only for pure forest environments and for frequencies, which do not exceed 500 MHz [16,17]. The model developed in [18][19][20][21] takes into account the layer of discrete scatterers, as cylinders and disks, which model trees and their branches and leaves, using singlescattering approximation (Born approximation) cannot be converted to the mixed areas containing trees and houses. Models created for rough terrain, including sea surfaces [27][28][29][30][31][32], cannot be used for forested and built-up areas with complicated profiles of the terrain.…”

Cuda Implementation in the Em Scattering of a Three-Layer Canopy

“…For sparse media like vegetation, Foldy's approximation [29][30][31][32][33] can be employed to account for the absorption and scattering effects introduced by the medium. The propagation of coherent wave with E v and E h as the horizontal and vertical components of the electric field is governed by where s is the distance along the direction of propagation, and…”