本文選題：雷達散射截面 + 射線追蹤��； 參考：《西安電子科技大學》2015年碩士論文

【摘要】：由于實際中目標結構和組合材料的復雜性,其結構組成并非單一幾何體,材料構成也并非單一金屬或非金屬材料,因此,對不同材料、不同組合體的電磁散射特性的研究具有迫切的需求�；贛axwell方程的物理光學(PO)算法,被公認在高頻電磁場計算領域具有極佳的適用性,特別對電大尺寸目標的散射及輻射問題能夠給出滿意的結果。而作為射線光學中的一種零波長近似,幾何光學(GO)理論,以其在均勻媒質平面波下對能量傳播和散射機理方面獨有的處理優(yōu)勢,能夠對給定結構進行射線追蹤。本文在結合PO及GO算法各自優(yōu)勢的基礎上,分析并實現(xiàn)了PO算法及幾何物理光學(GO-PO)算法,并對介質目標下各算法的反射系數(shù)進行修正。重點結合兩種電磁計算方法,從簡單到組合模型及復雜目標再到介質涂覆目標,對大量算例作出具體的電磁仿真、計算及分析。詳細的工作包括:1.結合PO經驗公式分析并求解了標準體(圓盤、方板)在不同情況下的雷達散射截面(RCS),采用Mie級數(shù)法對球體和圓柱的散射場進行求解分析。在此基礎上進一步實現(xiàn)了對任意目標的RCS的PO理論計算,以不同模型的求解算例作為參考依據,驗證了算法的可靠性和通用性。2.在實現(xiàn)PO對一次場求解的基礎上,引入GO中的射線追蹤思想來增加多次反射場對總場的貢獻,對目標進行三角面元剖分,對各個面元進行一次及多次場的求解,并對各個面元的場進行相干疊加,最終實現(xiàn)了GO-PO理論對任意模型的總場的計算。詳細求解并分析了二面角結構不同夾角、尺寸,入射波不同頻率、不同極化方式下的耦合場。特別對于類海面與船舷結構,采用正弦型組合粗糙面進行模擬,船舷用平板簡化表示,正弦面代替粗糙面。分析了復合結構中夾角、粗糙海面起伏大小對電磁散射特性的影響,為船海耦合電磁散射特性分析提供了基礎模型。并對組合目標(三面角結構、船體桅桿雷達簡易組合模型)及復雜目標例如小型飛機的耦合場進行了求解。3.對比不同極化方式(HH、VV)下介質材料特性的變化,結合不同介質對PO及GO-PO算法的反射系數(shù)進行修正,實現(xiàn)了介質目標的PO及GO-PO求解。利用介質PO求解了涂覆介質的方板及圓錐的散射場。采用介質GO-PO算法解決了涂覆不同介質、不同涂覆位置的二面角結構的耦合場的計算問題。另外對組合目標比如類海面與船舷結構涂覆介質、甲板和陣列天線涂覆不同介質以及復雜目標比如導彈模型涂覆介質情況都作出詳細的計算與分析。并結合大量算例作為理論依據,分析了介質材料(無耗和有耗介質)對目標RCS影響方面作出的貢獻。
[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.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN011

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本文編號：1979384