特征基函数法及其改进技术在电磁散射中的应用

发布时间：2018-05-11 02:29

本文选题：雷达散射截面 + 矩量法　；参考：《安徽大学》2017年博士论文

【摘要】：目标电磁散射特性的研究对于雷达系统的设计、目标隐身与反隐身技术研究、基于雷达回波信号的目标识别研究等应用都有极其重要的价值。目标电磁散射特性的数据固然可以通过测量获取,但是要求具备昂贵的测量设备、理想的测量环境,需要耗费大量的人力、物力和财力,还需要较长的测试周期,成本代价极高。相比之下,通过理论建模和数值模拟的途径来分析目标电磁散射特性则更加便捷,成本更低。因此如何快速高精度分析电大目标电磁散射问题是计算电磁学一直以来的研究热点之一。本文在此背景下,紧密围绕提高计算精度和计算效率这两个关键问题,对基于矩量法的多层特征基函数法及其改进技术展开研究,并将其应用到电磁散射问题的分析中。本文研究主要分为两个部分,第一部分是从计算效率和计算精度这两个问题出发,对多层特征基函数法及其改进技术展开研究;第二部分对特征基函数法的应用进行扩展。提出一种融合特征基函数法,并应用该方法快速精确分析多激励入射下导体目标电磁散射特性。在第一部分中,针对特征基函数法在分析电大导体目标电磁散射特性时,为了控制子域的个数,每个子域中未知量数目就不得不增加,从而使得特征基函数生成过程非常耗时的问题,首先将基于Foldy-Lax多径散射方程的单层特征基函数法扩展为多层特征基函数法,以此来提高未知量的压缩率;同时采用自适应交叉近似法对每一层的阻抗矩阵进行压缩填充,加速缩减矩阵的构造。数值结果显示该方法可以有效提高计算效率降低内存需求。其次,提出了一种快速精确的基于多层特征基函数法的混合方法。在混合方法中,提出一种修正的快速偶极子法来改善传统快速偶极子法的计算效率和计算精度;随后将修正的快速偶极子法与自适应交叉近似法及等效偶极子法相结合来提高多层特征基函数法的计算效率。应用修正的快速偶极子法后,次要特征基函数的生成和缩减矩阵的构造更加高效,结果也更加精确。当远场组判距条件变得苛刻以此来获得更精确的结果时,由于中间场的阻抗矩阵运用了自适应交叉近似法进行压缩,使得整个混合方法计算效率得以进一步提高,内存需求进一步减少。数值结果不仅证明修正的快速偶极子法可以有效减少计算时间和减小相对误差,还证明了在给定的相同远场组判距条件下,混合方法可以提高计算效率降低内存需求。在第二部分中,针对特征基函数法在多激励入射导体目标电磁散射问题分析中的应用,提出一种融合特征基函数法。首先,新定义一种改进的主要特征基函数,将周围子域的影响考虑进每个子域的主要特征基函数中,丢弃一阶次要特征基的同时采用高阶特征基来提高最终结果的精确度。因为每一个特征基函数中都考虑了子域与子域之间的互耦效应,所以只需要极少数量的入射平面波就可以获得具有较高精度的结果,从而实现精度与效率的同步提高。最后对多层特征基函数法及其改进技术进行总结分析,并对未来研究工作方向进行展望。
[Abstract]:The study of the target electromagnetic scattering characteristics is of great value to the design of radar system, the research of target stealth and anti stealth technology and the research on target recognition based on radar echo signal. The data of the target electromagnetic scattering characteristics can be obtained by measurement, but it is required to have expensive measurement equipment and ideal measurement. The environment requires a lot of manpower, material and financial resources. It also requires a long period of test, and the cost cost is very high. In contrast, it is more convenient and lower cost to analyze the target electromagnetic scattering by theoretical modeling and numerical simulation. Therefore, how to analyze the electromagnetic scattering problem of the large target fast and high precision is the computational electromagnetics. In this background, this paper focuses on two key problems of improving computing precision and computing efficiency, and studies the multi-layer characteristic base function method based on moment method and its improved technology, and applies it to the analysis of the electromagnetic scattering problem. This paper is divided into two parts, the first part From the two problems of computational efficiency and calculation accuracy, the multi-layer characteristic basis function method and its improved technology are studied. The second part extends the application of the characteristic basis function method. A fusion characteristic basis function method is proposed, and the method is applied to analyze the electromagnetic scattering characteristics of the conductor target quickly and accurately. In order to control the number of subdomains, the number of unknown quantities in each subdomain has to be increased in order to control the number of subdomains in the analysis of the electromagnetic scattering characteristics of the electrically large conductor targets in the part, which makes the generation of the feature base function very time-consuming. First, the single layer characteristic basis function method based on the Foldy-Lax multipath scattering equation is extended to be the first one. The multi-layer characteristic base function method is used to improve the compression rate of the unknown quantity. At the same time, the adaptive cross approximation method is used to compress the impedance matrix of each layer and accelerate the construction of the matrix. The numerical results show that the method can effectively improve the computational efficiency and reduce the memory requirement. Secondly, a fast and accurate multi layer based on multilayer is proposed. In the hybrid method, a modified fast dipole method is proposed to improve the computational efficiency and calculation accuracy of the traditional fast dipole method. Then the modified fast dipole method is combined with the adaptive cross approximation method and the equivalent dipole method to improve the computational efficiency of the multi-layer characteristic base function method. When the modified fast dipole method is applied, the construction of the secondary feature base function is more efficient and the result is more accurate. When the distance condition becomes more rigorous to obtain more accurate results, the impedance matrix of the intermediate field is compressed by the adaptive cross approximation method, which makes the whole mixing method. The computational efficiency is further improved and the memory demand is further reduced. The numerical results not only prove that the modified fast dipole method can effectively reduce the calculation time and reduce the relative error, but also proves that the hybrid method can improve the calculation efficiency to reduce the memory demand in the given distance of the same far field. In the second part, the needle is used. In this paper, a fusion characteristic basis function method is proposed for the application of the characteristic basis function method in the analysis of the electromagnetic scattering of multiple exciting incident conductor targets. First, a new improved main feature base function is defined, and the influence of the surrounding subdomains is taken into account in the main feature base functions of each subdomain, and the first secondary feature base is discarded and the higher order is adopted. The feature base improves the accuracy of the final result. Because each characteristic base function takes into account the mutual coupling effect between the subdomain and the subdomain, only a few number of incident plane waves can be obtained with high precision, so that the accuracy and efficiency can be improved synchronously. Finally, the multi-layer characteristic base function method and its modification are made. The technology is summarized and analyzed, and the future research direction is prospected.

【学位授予单位】：安徽大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN011

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