Research On High Frequency Method For Electromagnetic Scattering Modeling Of Dielectric Targets

Dielectric structures are widely used in man-made targets,such as low-scattering aircrafts,antenna radomes,buildings and so on.Efficient and accurate method for obtaining electromagnetic scattering from dielectric targets is helpful for design of low scattering aircrafts,analysis of dielectric radome’s scattering characteristics and through-wall radar imaging.It is of great academic significance and application value to develop an efficient electromagnetic scattering modeling method for complex dielectric targets by intensive studying its electromagnetic scattering mechanism.The electromagnetic scattering modeling of dielectric targets is more difficult than the electromagnetic scatering modeling of PEC target.In the modeling process,the geometric structure of the dielectric target is not only considered,but also the electromagnetic parameters and the spattial distribution of the material are taken into account.Based on the ray splitting tracing technique,the physical optics(PO)and the hybrid geometric optics and physical optics(GO-PO)algorithm is used to realize the high-frequency electromagnetic modeling of the electrically large size complex dielectric targets.A algorithm to judge the multi-interacted collision point is proposed,which effectively solves the problem about "depth of field" in the process of judging the collision point.At the same time,in addition to obtaining the electromagnetic properties of complex dielectric targets,it is also desirable to extract the information related to its geometric and physical properties from the scattering characteristics of the target for automatic target recognition(ATR).In the high frequency region,the scattering property of targets can be seen as the superposition of multiple isolated scattering centers,and the scattering center parameterization model can describe the scattering properties of the target succinctly.In this paper,based on geometric model and material electromagnetic parameters,a parametric forward modeling method for the scattering center of complex dielectric target is proposed.This method is based on the CAD model of complex dielectric targets And the electromagnetic parameters of the material.Firstly,parts disassembling method for complex dielectric target is studied,and the solid components marked with number are output.Then,the complex dielectric target’s strong scattering source decomposition and quantitative characterization technology is achieved.Through the ray tracing and clustering process,this technique establishes exact correspondence between the target strong scattering sources and target’s solid components.The effective separation,quantitative characterization and reasonable classification of strong scattering sources is realized,and the scattering response of a complex dielectric target is decomposed and approximated as a sum of responses from strong scattering centers.Strong scattering center models which are Quantity controllable and high precision are obtained.The strong scattering center model’s Electromagnetic scattering mechanism is clear.Furthermore,according to the high-frequency electromagnetic mechanism of complex dielectric targets,a set of forward method is developed to determine the physically relevant parameters of two-dimension(2-D)attributed scatterers for complex dielectric targets.The problem of forward projection of the three-dimensional(3-D)position parameter of the complex dielectric target’s scattering centers is overcame,and the attribute parameters of each scattering center are obtained.The forward modeling method of the complex dielectric target and its result have clear physical meaning.The separated scattering center and its parameters are corresponding to responses of the various solid components.The calculation of the modeling process is small,which can meet the needs of radar target online and quasi-real-time identification.Compared with the commonly used Template-based database,the amount of data is greatly compressed.The number of target scattering centers is controllable and target scattering centers are effective.The forward approach to establish parametric scattering center models for complex dielectric targets expands the scope of applications.