Study On Statistical Modeling Of Electromagnetic Scattering From Typical Ground Environment

The research of the interaction between electromagnetic wave and the surface of feature is to study the characteristics of electromagnetic scattering from the ground surface. So we can master the distribution features on the various conditions of ground clutter and then eliminate or reduce the influence of clutter. In high-resolution observation and target recognition of the ground, it is of great importance in theory and application. Based on the scattering properties of random Gaussian rough surface, some statistical models of typical ground are discussed and the characteristics of amplitude distribution and apatial correlation of bare soil, asphalt and cement concrete are obtained. A relevant basis for the statistical distribution fitting and SAR images simulation of the clutter is provided. The main work is as follows:1. Firstly, the background and significance of studying the scattering characteristics of rough surface are introduced. From two aspects which are the rough surface electromagnetic scattering and the statistical modeling of clutter, the current research situation and trend in domestic and foreign are described.2. Then, the random rough surface is simulated, and both the impact of different correlation length and root mean square of height on the rough surface are analyzed. Then it introduces several methods of computing electromagnetic scattering from rough surface and analyzes the Kirchhoff approximation and the two-scale method in detail.3. Thirdly, the backscattering coefficients of bare soil, asphalt and cement concrete is discussed. By comparing the Kirchhoff approximation with the two-scale method the scopes of the two methods are verified. The effects of different parameters on the backscattering coefficients are also studied.4. Finally, the unit field with the Kirchhoff approximation and the two-scale method is calculated. Because it requires a relatively clear texture feature in statistical modeling of clutter, the impacts of incident angle, the cell area and the polarization on the gray scale’s texture of scattered field are discussed under the Kirchhoff approximation in small incident angle. At the same time a analysis of the amplitude distribution characteristic of the scattering field under different circumstances is made. Then it introduces the variation of the distribution and gray scale about units scattered field by the two-scale method with a large incident angle. A detailed process of SAR images modeling of bare soil, asphalt andcement concrete with the Kirchhoff approximation is presented. And their SAR image amplitude distribution characteristic and normalization probability density are analyzed. Finally, it gives the spatial correlation of clutter, and analyzes the obtained SAR images including bare soil, asphait and cement concrete. The comparisons of the spatial correlation diagram with the original SAR image provide a basis for statistical distribution’s fitting and simulation of ground clutter in the future.