Statistical temporal behaviour of pulse wave propagation through continuous random media
Statistical temporal behaviour of pulse wave propagation through continuous random media
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DOI：
10.1088/0959-7174/13/1/304
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发表时间：
2003-01
期刊：
影响因子：
--
通讯作者：
Zhengwen Xu;Jian Wu;Zhensen Wu
中科院分区：
文献类型：
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作者：
Zhengwen Xu;Jian Wu;Zhensen Wu
摘要脉冲波在随机介质中传播时，由于背景介质和嵌入的不规则性，会发生到达时间的波动、时间展宽、偏斜度和峰度的变化等畸变。我们进行了研究的时间行为的电磁脉冲传播通过随机介质使用的时间矩和最近通过迭代获得的双频互相关函数的解析解。我们对待的时间特性顺序，首先得到一般表达式。然后给出了脉冲在湍流非色散大气和电离层中传播的简明形式，并对电离层进行了数值计算。结果表明，平均到达时间主要由群速传播项决定，背景介质的高阶色散和不规则体的随机散射对平均到达时间有较小的修正，但不规则体色散的修正很小，可以忽略。对于跨电离层传输的脉冲展宽，结果表明，在大多数情况下，背景电离层的色散和电子密度不规则体的散射对脉冲展宽的贡献很小，可以忽略不计。最后，我们发现跨电离层脉冲的时间偏度为负，能量向前沿移动，不规则体散射和色散的贡献大于背景散射和色散的贡献，因此背景散射和色散的贡献在大多数情况下可以忽略。
Abstract Pulse waves propagating through random media suffer distortions, such as fluctuation of arrival time, temporal broadening, and alteration of skewness and kurtosis, due to both the background medium and embedded irregularities. We carry out a study on the temporal behaviour of electromagnetic pulses propagating through random media using temporal moments and an analytic solution of a two-frequency mutual coherence function recently obtained by iteration. We treat the temporal characteristics sequentially, with general expressions obtained first. Then the concise forms are given for pulse propagation in the turbulent non-dispersive atmosphere and the ionosphere, with numerical calculations for the latter. The results show that the mean arrival time is dominated by the term propagating at group velocity, and small corrections arise from higher-order dispersion of the background medium and random scattering of irregularities, but the correction from dispersion of irregularities is neglected as it is so small. As for pulse broadening in trans-ionospheric propagation, the results show that contributions are mainly from the dispersion of the background ionosphere and scattering of electron density irregularities in most cases, and the contribution of dispersion of irregularities is so small that it can be neglected. Finally, we find that the temporal skewness of a trans-ionospheric pulse is negative and its energy is shifted to the leading edge, and the contributions from scattering and dispersion of irregularities dominate over those of background, so the latter can be neglected in most cases.