Study On The Characteristic Of Electromagnetic Scattering From The Rough Land Surface And Desert

In this thesis, fundamental theory of electromagnetic scattering from the rough surface is introduced for random rough surface models and electromagnetic scattering models, such as Kirchhoff Approximation and Small Perturbation Approximation. Models of longitudinal dune and transverse dune on the desert are presented. Backscattering coefficient of multiple scattering between dunes is derived. The influences of wavelength, dielectric constant, mean square root, correlation length and slope angular on the scattering coefficient from the rough surfaces with Exponential spectrum are analyzed, and numerical results are compared with Two-Scale Model for different desert models. According to the four-element model, the relation between humidity and dielectric constant of soil is presented and electromagnetic scattering from soil surface is calculated at different soils by Kirchhoff and Small Perturbation Method. Based on Scalar Approximation and Stationary-Phase Approximation, electromagnetic scattering and transmission in the medium under rough surface are investigated and formulae of transmission coefficients for different polarizations are presented and discussed numerically. The diagram of the scattering coefficient for different polarization transmission wave considering Exponential spectrum with varying of the scattering angle, the scattering azimuth angle and the frequency of the incident wave is obtained by numerical implementation. Finally, the first order electromagnetic scattering from layered model rough surfaces is also examined by applying the Small Perturbation Method and the comparison of scattering coefficients for the layered model and surface reflection are given and discussed in detail.