Study On Composite Scattering From Target Above Rough Surface With Grass

The study of composite scattering of actual complex environments and targets as an important part of modern warfare has received more and more extensive attention from research scholars at home and abroad.With the development of technological information,there is a higher demand for fast and effective analysis of the composite scattering characteristics of complex targets and environments.Smaller memory consumption and faster calculation of accurate results are important directions for future research.The study of the composite electromagnetic scattering of electrically large targets and rough surfaces is of great significance characteristics of actual complex environments and targets.However,the complexity and variability of the actual background environment present many difficulties for modelling complex environments and their complex electromagnetic scattering with targets.Many scholars have conducted their studies based on the MIMICS scattering model of forest vegetation,using ellipsoidal spheres and columns to approximate the simulation of longer stems and leaves in the vegetation layer,and have conducted many theoretical studies and practical measurements in this field,laying the foundation for the study of composite scattering of compound rough surfaces and complex targets.The problem of composite scattering of random rough surfaces and targets has been examined by many experts and scholars at home and abroad.In this paper,we study the composite electromagnetic scattering from target above the rough surface with grass.The electromagnetic scattering characteristics of the complex target is analyzed by SBR method.The composite scattering of the random rough surface and the target is calculated by SBR-PO method.Combine the electromagnetic scattering coefficient of vegetation layer calculated by vector radiation transmission equation,the final composite electromagnetic scattering result of target above the rough surfacewith grass is obtained.The main research work is as follows:1 3D modeling rhino software is used to geometrically model several typical targets involved in the research.Since the physical optical method does not consider the multiple scattering problem,there are certain limitations in dealing with the electromagnetic scattering problem of complex targets.Therefore,in this paper,the bouncing ray method(SBR)is used to calculate multiple scattering between complex target bins.In addition,the physical diffraction theory(PTD)is used to process the edge diffraction field of the model,the electromagnetic scattering model of electrically large-scale complex targets is established,and the simulation results with the fast multipole method(MLFMM)in the commercial software FEKO are compared.The accuracy of the SBR/PTD method in calculating the backward radar scattering cross section of complex electrically large targets is verified.Finally,based on the SBR/PTD method,the backscattering cross sections of several typical complex targets are calculated,and their electromagnetic scattering characteristics are analyzed.2.The scattering characteristics of monomeric targets in vegetation are treated using a dispersion model,the scattering characteristic of monomeric targets is analyzed by generalized Raylei GH-Gans approximation calculations,followed by a brief description of the many scattering methods for random rough surfaces,and a study focusing on the Kirchhoff method is present.3.Based on the MIMICS forest model,a simplified two-layer vegetation model is built and its scattering characteristics is analyzed with vector radiation transport theory.The formula for calculating the dielectric constant for vegetation and soil is derived.A detailed derivation of the vector radiation transport equation,a common method for studying vegetation scattering problems are presented.The relationship between the backward scattering coefficient and the angle of incidence of the bilayer vegetation scattering model is calculated.The relationship between the backward scattering coefficients of the bilayer vegetation scattering model and the mean square root height of the random rough surface,the density of monomer targets in the vegetation,the water content of the vegetation and soil,and the height of the vegetation are also discussed.4.Composite electromagnetic scattering characteristics of the composite rough surface with an electric large size target is analyzed in this paper.The total radar scattering cross section is obtained based on the four-path idea.The problem of second-order scattering for the existence of paths is solved by the Huygens principle considering the coupling role that exists.The accuracy of the SBR-PO method in dealing with composite scattering is verified by using a hybrid approach of SBR-PO to solve the composite electromagnetic scattering of the random rough surface and the upper target,and comparing the simulation results with those obtained by the fast multipole method(MLFMM)in the commercial software FEKO.For the problem of composite scattering of complex rough surface andcomplex electrically large size targets,a hybrid method of VRT and SBR-PO is proposed to investigate the relationship between the composite rough surface and the composite electromagnetic scattering of the target and the incidence angle,and the influence of the target height,vegetation percentage and density of single target particles in the vegetation on the final scattering results are also investigated.