海面蒸发波导对电磁波传播的影响

Effect of the Sea Surface Evaporation Duct on the Propagation of Electromagnetic Wave

阐述了电磁波传播的抛物近似方程数值模型及其步进类型的傅里叶变换解法,利用该模型对海面上高度30m的蒸发波导中的电磁波进行了数值模拟,并运用模拟结果分析了蒸发波导对电磁波的陷获作用;通过与标准大气折射环境情况进行对比,证实了海洋蒸发波导环境下雷达实施超视距探测的可行性;根据抛物近似方程模式,给出了电磁波在海洋边界层大气中的传播损耗计算式;最后,给出了电磁波被俘获到波导层中形成波导传播所满足的波长(频率)、发射角度以及发射源与蒸发波导所处的相对位置的关系。

This paper proposes a numerical model based on parabolic approximation equation for the propagation of the electromagnetic wave and analyzes its marehing type with Fourier transform algorithm. Numerical simulation is carried out for electromagnetic wave propagation in the evaporation duct at the altitude of 30 meters above the sea surface. From the results, the effect of evaporation duct in trapping electromagnetic waves is analyzed. As compared with ambient conditions of the standard atmospheric refraction, the feasibility of implementing radar transhorizon detection in the marine evaporation duct environments is clearly confirmed. The propagation loss function of electromagnetic waves under the condition of the ocean boundary layer atmosphere is obtained from the parabolic approximate equation mode. The relationship among the departure angle, the relative location of the evaporation duct with respect to the emission source and the wavelength （trequency） is derived, which determines the establishment of ducting propagation in the environments to capture electromagnetic waves.