A microwave propagation model for estimation of effective attenuation coefficients in a vegetation canopy

Abstract This article presents a detailed theoretical model for propagation of microwave in a layer of vegetation medium. The vegetation medium is modeled by a layer of randomly distributed dielectric circular disks and cylinders, representing the leaves and the stems, respectively. Propagation of wave in such a medium is taken as a transport of energy problem, and is formulated by a Monte Carlo method. Interactions of wave with the vegetation components are treated as a sequence of multiple scattering events between the photon flux and the scatterers. A Monte Carlo algorithm is used to track these collision processes, and the energy of the photon leaving the vegetation layer is collected. With sufficient number of photon histories, the ensemble averages of the photon energy are used to calculate the attenuation coefficients of the wave through the vegetation layer. Our simulation results indicate that attenuation coefficients calculated using this multiple scattering model may differ from those given by a simple single scattering model. Effects on the attenuation coefficients by various parameters such as moisture content, scatterer's size, and volume fraction are studied. Comparisons of the calculated results are made with the measured data and good match is obtained.