Abstract: The authors explain a double layers and plane valley electron density profile The coherence bandwidth of shortwave channel is calculated by using the density profile and wave propagation features in ionosphere Finally, coherence bandwidths for different operating frequencies and ground distances are obtained Because the double layers and plane valley model can analyze more exactly the multipath components and their path losses, it can obtain coherence bandwidths more closely to the measured values than those of the single layer model

Key words: shortwave channel, parabolic ionosphere, delay spread, coherence bandwidth

摘要： 介绍了一种双层平谷电离层电子密度模式。从该电子密度模式和电离层波传播特性出发确定多径分量，计算短波信道相干带宽。计算并分析了不同工作频率以及不同通信距离下的相干带宽。与采用单层电子密度的模型相比，由于双层平谷模型可以更准确地分析由电离层反射的多径分量以及它们的路径损耗，因此其计算的相干带宽比单层模型更接近实际测量值。

关键词: 短波信道, 抛物电离层, 时延扩展, 相干带宽