本文選題：電磁散射 + 彈跳射線法　； 參考：《西南交通大學(xué)》2015年碩士論文

【摘要】：在現(xiàn)代軍事科技以及通訊系統(tǒng)中,電磁場數(shù)值方法被廣泛應(yīng)用于復(fù)雜電磁環(huán)境的預(yù)估以及軍事目標(biāo)的分析探測等方面,具體途徑主要可分為兩類,高頻方法以及低頻方法,高頻方法主要用于處理電大尺寸同時結(jié)果相對簡單的目標(biāo),低頻數(shù)值方法主要用于處理結(jié)構(gòu)相對復(fù)雜的電小尺寸目標(biāo),但對于多尺度目標(biāo),使用一種方法進(jìn)行分析,難以同時滿足計算速度和精度的要求,所以使得二者的混合算法更加符合實際應(yīng)用。首先,本文對傳統(tǒng)彈跳射線法(SBR)的進(jìn)行了介紹。具體介紹了傳統(tǒng)算法中的射線追蹤求交方法,并推導(dǎo)了物理光學(xué)積分解析式。接著,針對表面基本由平面構(gòu)成的散射體,在傳統(tǒng)彈跳射線法(SBR)的基礎(chǔ)上,對射線跟蹤以及射線求交測試方法進(jìn)行改進(jìn)。研究了單根射線與三角形的快速求交方法,同時與彈跳射線法相結(jié)合,使用三角形對目標(biāo)進(jìn)行兩次表面擬合,分別得到用于求交測試的稀疏三角面元,以及用于射線追蹤的起始三角面元,利用快速求交方法,完成射線追蹤,進(jìn)行物理光學(xué)(PO)積分,完成目標(biāo)遠(yuǎn)場電磁散射的快速預(yù)估,將該方法的計算結(jié)果與文獻(xiàn)結(jié)果進(jìn)行對比,驗證了該方法的可靠性,通過計算不同擬合面元密度下情況下的結(jié)果,驗證了該算法的高效性。同時,在頻域SBR算法的基礎(chǔ)上,進(jìn)行了時域算法的研究,計算過程中遮擋判別和射線追蹤過程沿用頻域算法的方法,對于時域PO積分,采用類比Radon變換的一種方法進(jìn)行解析,得出了準(zhǔn)確的閉合表達(dá)式,通過對一次反射和多次反射模型的數(shù)值仿真,驗證了算法的正確性。最后,在時域算法的基礎(chǔ)上,進(jìn)行了TDSBR-FDTD混合算法的研究,將計算區(qū)域分為TDSBR計算區(qū)域和FDTD計算區(qū)域,兩區(qū)域采用近遠(yuǎn)場變換進(jìn)行數(shù)據(jù)交換,推導(dǎo)了基爾霍夫表面積分表達(dá)式,并對程序?qū)崿F(xiàn)中數(shù)據(jù)交換采用的數(shù)據(jù)存儲方法進(jìn)行介紹,采用線性插值使得數(shù)據(jù)交換過程更加簡潔,最后進(jìn)行了分別進(jìn)行了輻射問題模型以及散射問題模型進(jìn)行了數(shù)值仿真,通過對比,驗證了本文算法在處理多尺度目標(biāo)散射問題時的正確性與可行性。
[Abstract]:In modern military science and technology and communication system, electromagnetic field numerical method is widely used in the prediction of complex electromagnetic environment and the analysis and detection of military target. The specific ways can be divided into two kinds, high frequency method and low frequency method. The high-frequency method is mainly used to deal with the electrically large size targets with relatively simple results, while the low-frequency numerical method is mainly used to deal with the relatively complex electric small size targets, but for the multi-scale targets, a method is used to analyze them. It is difficult to meet the requirements of speed and precision, so the hybrid algorithm is more suitable for practical application. Firstly, the traditional bouncing ray method (SBR) is introduced in this paper. The method of ray tracing intersection in traditional algorithm is introduced in detail, and the analytical formula of physical optics integral is derived. Secondly, based on the traditional bouncing ray method (SBR), the method of ray tracing and ray intersection measurement is improved. In this paper, the fast intersection method of single ray and triangle is studied. At the same time, combining with the bouncing ray method, the triangle is used to fit the target twice, and the sparse triangular element is obtained for the intersection test. And the initial triangular plane used for ray tracing, using the fast intersection method to complete the ray tracing, to carry out the physical optics (PO) integral, to complete the fast prediction of the far-field electromagnetic scattering of the target, and to compare the calculated results with the results of the literature. The reliability of the method is verified, and the efficiency of the algorithm is verified by calculating the results under different surface density. At the same time, based on the frequency-domain SBR algorithm, the time-domain algorithm is studied. The method of frequency-domain algorithm is used in the process of occlusion discrimination and ray tracing. For the PO integral in time domain, a method of analogous Radon transform is used to analyze it. An accurate closed expression is obtained, and the correctness of the algorithm is verified by the numerical simulation of the primary reflection model and the multiple reflection model. Finally, the TDSBR-FDTD hybrid algorithm is studied on the basis of the time-domain algorithm. The computational region is divided into TDSBR computational region and FDTD computational region. The near far field transform is used to exchange data between the two regions, and the Kirchhoff surface integral expression is derived. The data storage method used in data exchange is introduced. The linear interpolation is used to make the data exchange process more concise. Finally, the radiation problem model and the scattering model are numerically simulated. The correctness and feasibility of the proposed algorithm in dealing with the multi-scale target scattering problem are verified by comparison.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：E11;O441.4

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本文編號：2058119