林朱红,顾婷婷. 各向异性电离层中沿地磁场取向有限长柱体目标的近场散射[J]. 电波科学学报,2024,39(1):46-55 + 141. DOI: 10.12265/j.cjors.2023179
      引用本文: 林朱红,顾婷婷. 各向异性电离层中沿地磁场取向有限长柱体目标的近场散射[J]. 电波科学学报,2024,39(1):46-55 + 141. DOI: 10.12265/j.cjors.2023179
      LIN Z H, GU T T. Near-field scattering of finite cylindrical targets along the geomagnetic field in the anisotropic ionosphere[J]. Chinese journal of radio science,2024,39(1):46-55 + 141. (in Chinese). DOI: 10.12265/j.cjors.2023179
      Citation: LIN Z H, GU T T. Near-field scattering of finite cylindrical targets along the geomagnetic field in the anisotropic ionosphere[J]. Chinese journal of radio science,2024,39(1):46-55 + 141. (in Chinese). DOI: 10.12265/j.cjors.2023179

      各向异性电离层中沿地磁场取向有限长柱体目标的近场散射

      Near-field scattering of finite cylindrical targets along the geomagnetic field in the anisotropic ionosphere

      • 摘要: 为了研究甚低频(very low frequency, VLF)电磁波对电离层中目标的近场散射机制,提出了一种VLF电磁波在该环境中对有限长金属和介质柱体近场散射的计算方法。首先,通过定义散射系数和交叉散射系数,分析各向异性电离层中电型波和磁型波激励下的散射矩阵;然后,根据积分方程法和矩量法,计算得到各向异性电离层中有限长金属和介质柱体的近区散射场和表面电流半解析表达式;最后,通过各向异性电离层中VLF波的特征波分析,给出柱体近区散射场中寻常波(O波)和非寻常波(E波)分量空间分布情况。计算结果表明:电离层中VLF波在金属和介质目标表面激励了不同的电流,并在不同的电离层环境参数、柱体尺寸和入射角度下产生相应的近场散射和耦合散射;通过对比O波和E波表面电流分布和散射分量,进一步揭示了VLF波与暴露在均匀等离子体环境中的柱体目标的散射机理。本文的计算方法和结果可为电离层中散射通信和目标探测提供理论依据。

         

        Abstract: In the study of the scattering mechanism of very low frequency (VLF) waves on targets in the ionosphere, we propose a method for near-field scattering of VLF waves on finite-length conducting and dielectric cylinders in the ionosphere. Firstly, the scattering matrix under the excitation of electric and magnetic waves in the anisotropic ionosphere is analyzed by defining co- and cross-scattering coefficients; Then, based on the integral equation (IE) method and the method of moment (MoM), the semi-analytical expressions are obtained for near-field scattering and surface current of conducting and dielectric cylinder in the anisotropic ionosphere; Finally, by analyzing the characteristic waves of VLF waves in the anisotropic ionosphere, the spatial distribution of ordinary-waves (O-waves) and extraordinary-waves (E-waves) components are given in the near-field scattering of the scatterer. Numerical results indicate that VLF waves in the ionosphere excite different surface current on conducting and dielectric targets, which generates near-field scattering and coupled-scattering by different ionospheric environmental parameters, cylinder size, and incidence angles. Comparing current distribution and scattering components of O- and E-waves, the scattering mechanism between VLF waves and cylindrical targets exposed to uniform plasma is further revealed. The calculation method and results in this paper provide theoretical basis for scattering communication and target detection in the ionosphere.

         

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