电磁脉冲信号电离层传播的时间特性

摘要

研究背景电离层以及分布于其中的电子密度不规则性结构的变化，对穿越于其中电磁脉冲信号的传播时间产生的影响。基于积分方程迭代法得到的时间矩和双频、双点互相干函数的解析解，从理论分析和数值模拟，探讨电磁脉冲信号穿过电离层随机介质传播的时延特性，并基于极区背景电离层参数，模拟分析脉冲信号的附加时延随电离层电子密度不规则体谱指数，内、外尺度以及电子密度起伏方差等的变化。理论和数值模拟表明，电离层脉冲信号传播的时延取决于背景电离层以及相应的群速传播项的影响，而电离层不规则体的色散、散射作用对电磁脉冲信号附加时延的影响相对较小，两者在数量级上相差数十倍。%The background ionosphere and the irregularity in structure of electronic density have a serious influence on the time delay of the electromagnetic pulse signal propagation.Based on the analytical solution of the two-frequency mutual coherence function which is derived from the iterative method of integral equation,the time delay characteristics of electromagnetic pulse wave propagates through the ionosphere are simulated and discussed in detail.The excess delay of pulse wave changes with the spectral index of electron density irregularities,the inner and outer scale,the fluctuation variance of electron density and other parameters are analyzed with the parameters in the polar region ionosphere.The results show that the time delay of the pulse wave is mainly determined by the dispersion and scattering of the background ionosphere as well as the propagation items of the group velocity,the dispersion and scattering from the ir-regularities of the electronic density show a little impact on it,and both of them have more than 10 times difference in magnitude.