【作者】 李建富；

【导师】 邵可然；

【作者基本信息】 华中科技大学 ， 电机与电器， 2007， 硕士

【摘要】 在目前的军事探测中,雷达是重要的探测手段,等离子体隐身技术作为一种新概念,正受到越来越多的关注,美俄等国家都在进行深入研究并已进入应用阶段。开展电磁场在等离子体环境下散射场的研究,探索针对性的算法是非常必要的。目前应用于色散媒质电磁散射分析的方法主要是时域有限差分法(FDTD),它的原理简单明了,在处理复杂媒质问题时非常方便,但在遇到三维电大目标的散射问题时,计算量过大,并且FDTD方法本身也不是很精确。而时域积分方程法在求解这种问题时,对于均匀媒质只需离散散射体表面,相对于还要增加截断边界的FDTD,减少了很多未知量,同时TDIE也是一种精确的方法,不存在色散误差。若配合最近的时域平面波法(PWTD)进行加速,可望达到比较高的计算效率,是一种值得深入研究的数值方法。鉴于此,本文研究了三维目标瞬态电磁散射的TDIE方法,以期为将来将TDIE运用于等离子体色散媒质中打下一定基础。本文首先简要分析了课题的意义现状,与当前常见的几种数值方法作出比较后,说明了TDIE求解此类问题所具有的优势,以及存在的问题及解决方案。接着推导了时域电场、磁场、混合场的积分方程,并介绍了求解TDIE的基础:矩量法。在第四章,系统细致地分析了如何离散散射体,处理原始数据,如何用时间空间基函数展开TDIE,并进行内积检验,求取积分值及奇异积分。还分析了TDIE的稳定性问题以及解决方法,选取了一种新的抵制振荡的平均方法。算例表明,这种方法具有很好的效果。最后,浅谈了TDIE的快速算法PWTD的原理。这种方法能够使TDIE应用于复杂的色散媒质如等离子体,并且能把计算复杂度大大降低。这是TDIE的一个重大突破,是TDIE发展的新方向。更多还原

【Abstract】 In the current military detecting, the radar is an important means of detection. As a new concept, the plasma stealth technology is receiving more and more attention. The United States and Russia and other countries are carrying out in-depth research and have entered the application stage. To study the scattering electromagnetic fields in the plasma environment, and to explore specific algorithm is very necessary.The mostly used method in dispersive media for electromagnetic scattering analysis is finite-difference time-domain (FDTD). It is simple and clear, very convenient in addressing complex medium problems, but in the face of Electrically Large goals scattering problem, the calculation is excessive, besides the FDTD method itself is not very precise. On the other hand, when using the time-domain integral equation method to solve such problem, not only just the surface of scattering object is needed to be meshed for the homogeneous medium, but also a lot of unknowns will be reduced. Meanwhile, TDIE is more accurate, it does not produce dispersion error. When used with the plane-wave time-domain (PWTD) accelerating it is expected to achieve high computational efficiency and is a numerical methods worthy of in-depth study.As such, this paper presents a three-dimensional transient electromagnetic scattering using TDIE, hoping to lay the foundation of TDIE based numerical simulation applied in plasma dispersion medium in the future.This paper analyzes the significance of the status issue first. In comparing with the current common numerical methods, the advantages of TDIE based scheme solving such problems are shown. Then the integral equation time domain for the electric field, magnetic field, and the mixed field are derived, and the basis of the solution of TDIE : Moment Method is introduced.In the fourth chapter, this paper detailed analysis of how to get the discrete scattering body, how to deal with raw data, how to use space-time basis function, how to apply testing procedure and how to evaluate integral values and singular integrals. The stability of the TDIE solution is also analyzed and a new averaging method is used to resist the oscillation. The numerical results of two samples show that this method is very effective. Finally, the principle of the fast algorithm of TDIE : PWTD is briefly discussed. This approach enables TDIE to suit for complex dispersion medium such as plasma, and the computational complexity can also be reduced significantly. This is a major breakthrough for TDIE, and a new direction.更多还原