Analytical Approximate Model Of Electromagnetic Scattering From Random Rough Surfaces And Its Imaging Stud

The study for electromagnetic scattering characteristics from random rough surface is one of the research focuses currently,which plays a significance role in the land and sea surface parameter inversion and radar environmental monitoring imaging.Based on the statistical parameters of random rough surface,firstly,the scattering characteristics of single scale and compound random rough surface are studied in this thesis.Then,the radar imaging of rough surface is exploded by applying the surface facet scattering model of random rough surface.In the first part of this thesis,the electromagnetic scattering approximation models for single scale rough surface,namely the Integral Equation Method(IEM)and the Advanced Integral Equation Method(AIEM),are studied.Then the influences of different surface slope treatment schemes on the predicted values of AIEM model are compared with the measured data.Moreover,the prediction accuracy of both the AIEM model and the IEM model is verified by the measured data.Finally,an Advanced Two-Scale Model(ATSM)is proposed to analyze the electromagnetic scattering characteristics of composite rough surfaces.In the proposed ATSM,the Kirchhoff Approximation method(KA)is used to calculate the large scale rough surface,and the AIEM model is used to calculate the small scale rough surface.Compared with the numerical method PMCHWT and the Shooting Bounce Ray method(SBR),it is verified that the advanced two-scale model has a wider applicability than the traditional Two-Scale Model(TSM).Moreover,the prediction result of the proposed ATSM is more accurate than that of the traditional TSM.In the second part of this thesis,the electromagnetic scattering model of rough surface based on surface facet is proposed,including the KA facet scattering model,the AIEM facet scattering model for single rough surface and the ATSM facet scattering model for composite rough surface.For electromagnetic scattering from composite rough surfaces,the mirror scattering is calculated by the KA facet scattering model,and the diffuse scattering is calculated by the AIEM facet scattering model.Then,the rationality of the ATSM facet scattering model is proved by combining the measured data.The electromagnetic scattering model based on surface facet can not only get the mean scattering value of rough surface at different angles,but also get the spatial distribution of scattering coefficient at certain angles.Based on this characteristic,the surface facet scattering model is applied to Range Doppler imaging theory to realize the SAR imaging of typical rough surface.