Simulation Method Of EM Scattering From Layered Rough Surface And Its Application In Snow

Surface and sea surface in nature can be approximately simulated as random rough surface satisfying a certain probability density distribution function.But the environment in nature is very complex.There are two layers of rough surface in nature,such as soil surface covered with snow,grassland,soil surface covered with vegetation and so on.There are also three or more layers of rough surface.By studying the electromagnetic scattering characteristics of layered rough surfaces,We can detect and identify the buried materials under rough surface,study the scattering of complex marine background environment and so on.There is no doubt that the study of electromagnetic scattering from layered rough surfaces has significant theoretical significance and broad application prospects in both engineering and civil fields.This paper focuses on the research and discussion of the electromagnetic scattering characteristics of snow.The main work includes the following aspects:1.The geometric model and electromagnetic modeling method of rough surface are studied.Firstly,the Rayleigh criterion for judging the roughness of the rough surface and the statistical parameters commonly used for the rough surface are described.The Monte-carlo simulation modeling method of rough surface is also described.Secondly,the rough surface modeling method is used to simulate the typical rough surface.Finally,the related theory of electromagnetic scattering and the electromagnetic scattering calculation method of single-layer rough surface are emphasized,including: physical optics(PO)and small slope approximation(SSA).The influence of the statistical parameters of two typical rough surfaces on their two-station scattering coefficient and backscattering coefficient is analyzed.2.The geometric modeling and electromagnetic scattering calculation method of two-dimensional layered rough surface are studied.Firstly,the geometric modeling of two-dimensional layered rough surface based on Monte Carlo method is introduced.Secondly,the electromagnetic scattering and transmission of electromagnetic waves in two-dimensional layered rough surface are introduced,and the related problems of scattering coefficient and complex scattering angle in the two-dimensional layered rough surface propagation of electromagnetic waves are analyzed in detail.Finally,three typical two-dimensional layered rough surface models are established and their electromagnetic scattering characteristics are analyzed.The effectiveness of the calculation method is proved by calculating the electromagnetic scattering of the double-layer rough surface with the roughness of 0.The effects of the smooth surface of the upper rough surface and the statistical parameters of the two rough surfaces on electromagnetic scattering are calculated.3.The electromagnetic scattering characteristics of snow are studied.Firstly,the influence of dielectric constant on scattering is introduced.The calculation methods of different snow types and soil dielectric constants are studied.The effects of frequency and water content on different snow types and soil dielectric constants are analyzed.Secondly,the microwave characteristics of snow are analyzed.The transmission depth of snow is studied based on the energy variation during electromagnetic wave propagation.On this basis,the propagation characteristics of electromagnetic waves in snow are analyzed,and the electromagnetic scattering model of snow is determined.Finally,the effects of various statistical parameters of snow on the electromagnetic scattering of snow,including the polarization of electromagnetic waves,the roughness of the snow layer,the humidity of the soil,etc.,are analyzed.