Investigation On Electromagnetic Scattering Of Vegetation Model On Rough Ground Surface

The electromagnetic scattering characteristic of vegetation on rough ground surface is researched by combining experimental measurement in this thesis. Based on the electromagnetic scattering from rough surface with the shadowing effect by Kirchhoff Approximation, the MIMICS scattering model is modified to achieve the two-layered vegetation scattering model. The electromagnetic scattering of two-layered and three-layered vegetation is investigated by the vector radiative transfer equation (VRT) and Monte-Carlo method. The main contributions of the thesis are as following:1. The generalized Rayleigh-Gans approximation is used to calculate the scattering field from the single scatter in vegetation layer. By adopting the field inside the finite cylinder instead of that of an infinite cylinder, the scattering from a finite cylinder is calculated.2. The zero-order solution and the first-order solution of two-layered vegetation model are computed by the VRT theory. The backscattering coefficient of wheat versus the incident angle is analyzed, and the impact of vegetation moisture and ground moisture on scattering feature is also presented.3. The Monte-Carlo simulation is utilized to study the scattering from clustered vegetation on rough ground surface. The single scattering is used to calculate approximately the scattering of scatter in vegetation, and the phase differences are considered. The effect of clustered structure on scattering from vegetation is studied, including the backscattering coefficient versus the position distribution and the incidence frequency. The backscattering enhancement caused by the scatter-ground interaction is investigated. The relationship between the angle-width and the incidence frequency, as well as the height of vegetation, is considered.4. Based on the second-order scattered field, the coherent scattering model of three-layered vegetation is established. The Monte-Carlo method is also applied to calculate the backscattering coefficient of the model for different frequency. The numerical result is compared with that by the VRT method to validate the accuracy of our model.