大气波导环境中复杂地形条件下电磁波双程后向散射效应及其应用研究

Atmospheric duct is a nearly permanent propagation mechanism due to the abrupt changes in the vertical temperature and humidity profiles just above the surface layer and an anomalous structure obviously different from the standard atmosphere, which can cause EM-wave rays lying in the evaporation duct refracted towards the surface of the earth and make EM-power trapped or guided in a thin tropospheric layer above the earth. The Northwest inland regions and the Southeast coast and the adjacent sea area of China have the high probability of the atmospheric duct, and the related research has become an important frontier in the research field of the radio wave propagation. For the present bottleneck problem resulting from the parabolic equation ignoring the backscattering effect and lacking of the exact solution for the propagation space greater than 15 degree with the horizontal, the following will be studied from the point of view of the radio-wave propagation theory and the Computational Electromagnetics. Firstly, the wide-angle parabolic equation satisfied with the impedance boundary conditions for the complex terrains should be built, and the transform should be solved form the physical boundary to the numeric domain. Secondly, on the condition of considering the backscattering effect, the mixed Fourier split-step method for the parabolic equation can be presented and calculated on the complex impedance boundary conditions. Thirdly, the radio-wave propagation characteristics for the one-station radar should be analysized on complex terrain in atmospheric duct environment after considering the two-way backscattering effect. Through the research, a fast, efficient and accurate algorithm for the electromagnetic field can be realized in the atmospheric duct environment on the condition of complex terrain. And the work will provide a theoretical basis and technical support for the Electronics Design, performance optimization and evaluation of the China's National Defense Weapon System.

大气波导是由于近海面大气修正折射率随高度反常下降，使电波射线向下弯曲的曲率大于地球表面的曲率，从而将电磁能量陷获在波导结构内的电磁波异常传播现象。我国的西北内陆区和东南沿海及邻海区是大气波导高概率发生区，相关研究已成为当前电波传播研究领域的重要前沿。本申请针对抛物型方程忽略了后向散射效应以及对与水平线成15度以上传播区域精确求解的瓶颈问题，从电波传播理论和计算电磁学的角度研究：（1）建立满足复杂地形阻抗边界条件的宽角抛物型方程，解决气海边界物理域到数值域的变换方法；（2）实现考虑后向散射效应以及复杂地形阻抗边界条件下抛物型方程的混和傅立叶分步算法；（3）研究大气波导环境中复杂地形条件下单站雷达考虑后向散射效应时的电波传播特性。通过研究实现大气波导环境中复杂地形条件下电磁场的快速、高效、精确计算，此方面的研究突破将为我国国防中电子武器系统的总体设计、性能优化和评估提供理论依据和技术支持。

大气波导是由于近海面大气修正折射率随高度的反常下降，使电波射线向下弯曲的曲率大于地球表面的曲率，从而将电磁能量陷获在波导结构内的电磁波异常传播现象。我国的西北内陆区和东南沿海及邻海区是波导高概率发生区，相关研究已成为当前电波传播研究领域的重要前沿。项目针对抛物型方程忽略了后向散射效应以及对与水平线成15度以上传播区域精确求解的瓶颈问题，从电波传播理论和计算电磁学的角度研究：（1）解决气海边界物理域到数值域的变换方法，建立满足复杂地形阻抗边界条件的宽角抛物型方程；（2）实现考虑后向散射效应以及复杂地形阻抗边界条件下抛物型方程的混和傅立叶分步算法，提高了大气不均匀以及复杂地形环境中电波传播问题的数值求解精度及效率。通过研究实现大气波导环境中复杂地形条件下电磁场的快速、高效、精确计算，此方面的研究突破将为我国国防中电子武器系统的总体设计、性能优化和评估提供理论依据和技术支持。