基于TDSBR-FDTD混合算法的多尺度目标电磁散射研究

发布时间：2018-06-23 19:13

本文选题：电磁散射 + 弹跳射线法　；参考：《西南交通大学》2015年硕士论文

【摘要】：在现代军事科技以及通讯系统中,电磁场数值方法被广泛应用于复杂电磁环境的预估以及军事目标的分析探测等方面,具体途径主要可分为两类,高频方法以及低频方法,高频方法主要用于处理电大尺寸同时结果相对简单的目标,低频数值方法主要用于处理结构相对复杂的电小尺寸目标,但对于多尺度目标,使用一种方法进行分析,难以同时满足计算速度和精度的要求,所以使得二者的混合算法更加符合实际应用。首先,本文对传统弹跳射线法(SBR)的进行了介绍。具体介绍了传统算法中的射线追踪求交方法,并推导了物理光学积分解析式。接着,针对表面基本由平面构成的散射体,在传统弹跳射线法(SBR)的基础上,对射线跟踪以及射线求交测试方法进行改进。研究了单根射线与三角形的快速求交方法,同时与弹跳射线法相结合,使用三角形对目标进行两次表面拟合,分别得到用于求交测试的稀疏三角面元,以及用于射线追踪的起始三角面元,利用快速求交方法,完成射线追踪,进行物理光学(PO)积分,完成目标远场电磁散射的快速预估,将该方法的计算结果与文献结果进行对比,验证了该方法的可靠性,通过计算不同拟合面元密度下情况下的结果,验证了该算法的高效性。同时,在频域SBR算法的基础上,进行了时域算法的研究,计算过程中遮挡判别和射线追踪过程沿用频域算法的方法,对于时域PO积分,采用类比Radon变换的一种方法进行解析,得出了准确的闭合表达式,通过对一次反射和多次反射模型的数值仿真,验证了算法的正确性。最后,在时域算法的基础上,进行了TDSBR-FDTD混合算法的研究,将计算区域分为TDSBR计算区域和FDTD计算区域,两区域采用近远场变换进行数据交换,推导了基尔霍夫表面积分表达式,并对程序实现中数据交换采用的数据存储方法进行介绍,采用线性插值使得数据交换过程更加简洁,最后进行了分别进行了辐射问题模型以及散射问题模型进行了数值仿真,通过对比,验证了本文算法在处理多尺度目标散射问题时的正确性与可行性。
[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.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：E11;O441.4

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