大区域复杂环境的电磁建模及快速算法研究

The large area complex environment, in which the numerous electromagnetic signals interact with the surrounding geography and weather factors, can make important impacts on the equipment and personnel. The researches on electromagnetic modeling and efficient algorithms for the large area complex environment are useful in the in-depth analysis of its radiowave propagation law. It has important scientific value and application prospects. However, its current study is still in the initial stage. The development is mainly limited to the issues that how to fully consider the interaction between the electromagnetic wave and its surrounding environment, and how to achieve a good balance between calculation accuracy and speed. In this study, the key components in the large area complex environment will be analyzed and the electromagnetic modeling technology for various geographies and weathers based on parabolic equation will be developed. We will study the efficient numerical solution of the parabolic equation method and its massively parallel technology. We will also explore the techniques of the parabolic equation method in dealing with the electromagnetic pulse problem and the ultra wide angle problem. The finite difference time domain method with sub-grid of the separated time and space will be utilized to deal with some local simulation problems by the seamless connection technology between different algorithms. These algorithms construct a computable electromagnetic model for the large area complex environment, which contains various geography factors, weather factors and radiation sources. Finally, a massively parallel code for this model will be implemented, which can be applied to compute the distribution of electromagnetic field in the large area complex environment.

大区域复杂环境中存在着数量繁多、动态交叠的多种电磁信号，它与周围地理及气象环境综合作用，将对设备和人员等目标产生重要影响。大区域复杂环境的电磁建模及快速算法研究有助于深入分析其中的电波传播规律，具有重要的科学价值和应用前景。目前的研究还处于起步阶段，如何充分反映电磁波与周围环境的相互作用，以及如何实现计算精度与计算速度的良好均衡，是当前发展的主要瓶颈。本项目拟从大区域复杂环境的构成要素和作用机理出发，以抛物方程方法为核心，研究与之相适应的地理及气象环境的电磁建模技术、高效数值解法和大规模并行技术，探索抛物方程方法对电磁脉冲与超宽角求解问题的处理方法，并结合新型时空分离亚网格时域有限差分法，研究算法间的无缝连接技术，构建满足实际精度要求的包含多变地理、气象环境及多类型辐射源的大区域复杂环境电磁模型。最后，形成高效、高置信度的大规模并行仿真程序，快速准确计算大区域复杂环境中电磁场的时空分布。

在无线电波传播时，大区域地理环境和气象环境都会对电磁波产生较大的影响：这将极大地影响目标识别、遥感、无线通信等的效果。因此，展开大区域环境的电磁建模及快速算法研究具有重要的应用价值。.本课题对复杂环境的地形、森林、粗糙海面、大气波导、雨雾及沙尘暴媒质的电磁建模技术进行深入研究，构建了全面的、适用于公里级大区域复杂地理和气象环境的电波传播模型，分析了复杂环境对电磁波的综合作用；在此基础上，对抛物方程的非均匀网格模型、亚网格模型等高效网格模型，以及基于JASMIN的并行方法展开深入研究，能在保证计算误差不变的情况下大幅降低计算量与计算耗时，实现了计算精度与计算效率的良好均衡；研究了抛物方程法的电磁脉冲传播问题，结合新型时空分离亚网格时域有限差分法，形成区域级和目标级的协同计算，完成了区域环境中精细目标结构的时域波形求解；最后，结合第三方获取的数字高程影像地图，快速准确地计算大区域复杂综合环境中的电磁场时空分布。.本课题对复杂地理气象环境电磁建模技术及其高效算法进行了深入研究，能更好地为遥感遥测、移动通信网络室内覆盖优化、大区域环境中的电磁兼容分析等应用提供理论指导，具有重要的研究价值和意义。