组合体目标电磁散射的GO-PO算法

发布时间：2018-06-04 23:43

本文选题：雷达散射截面 + 射线追踪　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：由于实际中目标结构和组合材料的复杂性,其结构组成并非单一几何体,材料构成也并非单一金属或非金属材料,因此,对不同材料、不同组合体的电磁散射特性的研究具有迫切的需求。基于Maxwell方程的物理光学(PO)算法,被公认在高频电磁场计算领域具有极佳的适用性,特别对电大尺寸目标的散射及辐射问题能够给出满意的结果。而作为射线光学中的一种零波长近似,几何光学(GO)理论,以其在均匀媒质平面波下对能量传播和散射机理方面独有的处理优势,能够对给定结构进行射线追踪。本文在结合PO及GO算法各自优势的基础上,分析并实现了PO算法及几何物理光学(GO-PO)算法,并对介质目标下各算法的反射系数进行修正。重点结合两种电磁计算方法,从简单到组合模型及复杂目标再到介质涂覆目标,对大量算例作出具体的电磁仿真、计算及分析。详细的工作包括:1.结合PO经验公式分析并求解了标准体(圆盘、方板)在不同情况下的雷达散射截面(RCS),采用Mie级数法对球体和圆柱的散射场进行求解分析。在此基础上进一步实现了对任意目标的RCS的PO理论计算,以不同模型的求解算例作为参考依据,验证了算法的可靠性和通用性。2.在实现PO对一次场求解的基础上,引入GO中的射线追踪思想来增加多次反射场对总场的贡献,对目标进行三角面元剖分,对各个面元进行一次及多次场的求解,并对各个面元的场进行相干叠加,最终实现了GO-PO理论对任意模型的总场的计算。详细求解并分析了二面角结构不同夹角、尺寸,入射波不同频率、不同极化方式下的耦合场。特别对于类海面与船舷结构,采用正弦型组合粗糙面进行模拟,船舷用平板简化表示,正弦面代替粗糙面。分析了复合结构中夹角、粗糙海面起伏大小对电磁散射特性的影响,为船海耦合电磁散射特性分析提供了基础模型。并对组合目标(三面角结构、船体桅杆雷达简易组合模型)及复杂目标例如小型飞机的耦合场进行了求解。3.对比不同极化方式(HH、VV)下介质材料特性的变化,结合不同介质对PO及GO-PO算法的反射系数进行修正,实现了介质目标的PO及GO-PO求解。利用介质PO求解了涂覆介质的方板及圆锥的散射场。采用介质GO-PO算法解决了涂覆不同介质、不同涂覆位置的二面角结构的耦合场的计算问题。另外对组合目标比如类海面与船舷结构涂覆介质、甲板和阵列天线涂覆不同介质以及复杂目标比如导弹模型涂覆介质情况都作出详细的计算与分析。并结合大量算例作为理论依据,分析了介质材料(无耗和有耗介质)对目标RCS影响方面作出的贡献。
[Abstract]:Because of the complexity of the target structure and the composite material in practice, its structural composition is not a single geometry, nor is the material composition a single metallic or non-metallic material, so for different materials, There is an urgent need to study the electromagnetic scattering characteristics of different combinations. The physical optics (PO) algorithm based on Maxwell equation is recognized to be very suitable in the field of high frequency electromagnetic field calculation, especially for the scattering and radiation problems of electrically large targets. As a zero-wavelength approximation in ray optics, geometric optics (GOG) theory, with its unique processing advantage of energy propagation and scattering mechanism under plane wave of homogeneous medium, can trace a given structure by ray. Based on the advantages of PO and go algorithms, this paper analyzes and implements PO algorithm and GO-PO algorithm, and modifies the reflection coefficients of each algorithm under dielectric target. Combining two kinds of electromagnetic calculation methods, from simple to composite model and complex target to medium coated target, a large number of examples are simulated, calculated and analyzed. The detailed work includes: 1. The radar cross section (RCS) of standard body (disk, square plate) under different conditions is analyzed and solved by means of PO empirical formula. The scattering field of sphere and cylinder is solved by Mie series method. On this basis, the PO theory calculation of the RCS of arbitrary targets is further realized. The reliability and generality of the algorithm are verified by examples of solving different models. On the basis of the solution of PO to the primary field, the ray tracing idea in go is introduced to increase the contribution of multiple reflection fields to the total field, to divide the target into triangulated planes, and to solve the primary and multiple fields of each plane element. Finally, the GO-PO theory is used to calculate the total field of arbitrary model. The coupling fields of dihedral structure with different angles, dimensions, incident wave frequencies and polarization modes are solved and analyzed in detail. The sinusoidal combined rough surface is used to simulate the structure of sea surface and ship side, and the ship side is expressed simply by flat plate, and the sinusoidal surface is replaced by rough surface. The influence of the angle and the rough sea surface fluctuation on the electromagnetic scattering characteristics in the composite structure is analyzed, which provides a basic model for the analysis of the ship-sea coupling electromagnetic scattering characteristics. The coupling field of the combined target (trihedral structure, hull mast radar simple combination model) and complex target such as small aircraft is solved. By comparing the characteristics of dielectric materials under different polarization modes, the reflection coefficients of PO and GO-PO algorithms are modified in combination with different media, and the solution of PO and GO-PO for dielectric targets is realized. The scattering fields of square plates and cones coated with dielectric are solved by means of dielectric PO. The calculation of coupling field of dihedral angle structure coated with different medium and different coating position is solved by using medium GO-PO algorithm. In addition, detailed calculation and analysis of composite targets such as sea surface and ship side structure coated medium, deck and array antenna coated with different media and complex targets such as missile model coated medium are made. Based on a large number of examples, the contribution of dielectric materials (lossless and lossless media) to the target RCS is analyzed.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN011

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