确定HEMP近地面电磁环境是研究近地面电子设备的HEMP效应的基础。由于地面对电磁场具有反射作用, 使得近地面的电磁环境与自由空间的电磁脉冲环境相差较大。通过分析近地面HEMP传播特性以及土壤电气参数的不同, 建立不均匀媒质影响模型, 采用修正的菲涅尔反射系数对模型进行理论计算, 验证CST数值仿真方法的准确性及简便性, 并对近地面复杂电磁场环境进行仿真计算。结果表明: 不同波形、距地高度、上层厚度以及入射角度对HEMP影响较为明显, 不均匀媒质使得近地面HEMP电磁脉冲环境异于均匀媒质, 此结果能为指导近地面电磁脉冲防护提供基本依据。

Determining the near-surface electromagnetic environment of HEMP is the basis for studying the HEMP effect of near-surface electronic devices.Since the ground has a reflection effect on the electromagnetic field, the electromagnetic environment near the ground is quite different from the electromagnetic pulse environment in free space.By analyzing the propagation characteristics of near-surface HEMP and the difference of soil electrical parameters, an inhomogeneous media influence model was established.The modified Fresnel reflection coefficient was used to calculate the model, the accuracy and simplicity of CST numerical simulation method were validated, and a simulation was made to the near-surface complex electromagnetic environment.The results show that:1) The waveform, ground height, upper layer thickness and incident angle have obvious influence on HEMP;and 2) Inhomogeneous medium makes the near-surface HEMP electromagnetic pulse environment different from that of the homogeneous medium.The conclusion supplies a basic basis for guiding the near-surface electromagnetic pulse protection.