基于矩量法与渐近波形估计技术的动态海面宽带电磁散射特性研究

With the application of the wide band and ultra-wide band radar, more and more attentions have been attracted into the properties of the wide band electromagnetic scattering from the dynamic ocean surface. However, for the method of moments (MoM) and its associated frequency domain methods, there are several defects, such as repeated calculation, requiring more computational memory and computing time. In this project, we will try to solve the difficulties of the above methods. The calculation accuracy, memory requirement and computational efficiency will be taken into account at the same time. The properties of the wide band electromagnetic scattering from the one-dimensional dynamic ocean surface illuminated by the tapered plane wave and those of the two-dimensional dynamic ocean surface illuminated by the Gaussian beam will be calculated and analyzed. We focus on the properties of the one-dimensional dynamic ocean surface on low-grazing incident angle and those of the two-dimensional dynamic ocean surface under high sea condition.The MoM or the characteristic basis function method (CBFM) is firstly adopted to accurately obtain the electromagnetic scattering from the dynamic ocean surface at one or more sampling frequency. And then, the asymptotic waveform evaluation (AWE) technique is applied to obtain the rational fitting function within the scope of broadband electromagnetic scattering from the dynamic ocean surface. At the same time, the non-uniform rational B-spline (NURBS) surface modeling is introduced to reduce the number of unknowns of the two-dimensional dynamic ocean surface. This project will provide an operable technology for quantitatively analyzing of the wide band electromagnetic scattering from the dynamic ocean surface, and provide theoretical basis and technical support for the designing of the broadband or the ultra-wideband radar system, the detecting of targets moving on the dynamic ocean surface under high sea condition.

随着宽带和超宽带雷达信号的应用，动态海面的宽带电磁散射特性吸引了越来越多的关注，而以矩量法(MoM)为基础的频域计算方法存在多次重复计算、需要较多计算内存和计算时间的缺陷。本项目拟突破传统方法在解决该问题时计算精度、内存需求和计算效率无法兼顾的难题，以锥形波照射下一维动态海面和高斯波束照射下二维动态海面的宽带电磁散射特性为研究对象，重点围绕电磁波低掠角入射下一维及高海情二维动态海面宽带电磁散射特性进行研究。项目首先采用MoM或特征基函数方法(CBFM)精确获得一个或多个采样频点处动态海面的电磁散射，然后利用AWE技术获得宽带范围内动态海面电磁散射的有理拟合函数，同时，针对二维动态海面，引入非均匀有理B样条(NURBS)曲面建模技术减少未知量的个数。为动态海面宽带电磁散射的定量分析提供具有可操作性的技术手段，为宽带和超宽带雷达系统的设计、高海情动态海上运动目标的探测提供理论依据和技术支撑。

鉴于动态海面宽带电磁散射精确快速仿真算法的迫切需求，本项目借助于FEKO建立了二维粗糙面的非均匀有理B样条(NURBS)曲面模型，并模拟了其一维距离像和二维ISAR成像；利用渐近波形估计技术(AWE)研究了一维理想导体粗糙面的宽带电磁散射，同时为克服AWE在远离采样频点区域精度有限、计算复杂度较大的缺点，将梅利(Maehly)技术引入到一维介质粗糙面及其与目标(单个、多个)复合模型、二维粗糙面的宽带电磁散射的仿真研究中；采用特征基函数方法(CBFM)快速仿真了一维理想导体粗糙面电磁散射，并引入迭代收敛门限，运用自适应特征基函数(AMCBFM)方法提高了CBFM的收敛速度，同时将压缩感知(CS)引入到粗糙面电磁散射的快速计算中，并将AMCBFM于Maehly技术结合提高了粗糙面宽带电磁散射的计算速度。.另外本项目超额完成了两部分工作：采用支持向量机(SVM)研究了粗糙面的特征参数反演，开发了一款基于矩量法(MoM)的粗糙面电磁散射的仿真平台。.本项目的研究将为动态海面宽带电磁散射的定量分析提供具有可操作性的技术手段，为宽带和超宽带雷达系统的设计、高海情动态海上运动目标的探测提供一定的理论依据和技术支撑。