A general channel model for RF propagation through structured ionization
A general channel model for RF propagation through structured ionization
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DOI：
10.1029/91rs00263
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发表时间：
1991-07
期刊：
影响因子：
1.6
通讯作者：
R. Dana;L. A. Wittwer
中科院分区：
文献类型：
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作者：
R. Dana;L. A. Wittwer
用接收信号的二位置、双频、二时间互相关函数描述了电离层闪烁的二阶统计量。从麦克斯韦方程组推导互相干函数需要一个电离层电子密度波动的时间和空间变化模型。在泰勒的冻结假设下，电子密度波动被描述为漂移超过视线的刚性结构。因此，在电子密度的空间和时间波动之间存在确定性关系。当电离已经形成了一层与地磁场线对齐的薄条纹时，这个模型是准确的。在条纹形成之前或当电离层中存在具有不同相对速度的多个散射层时，湍流模型可能更合适。在完全湍流的情况下，电子密度的时空涨落是不相关的。现实应该介于这两个限制模型之间。本文介绍了一种介于冻结模型和湍流模型之间的通用模型。给出的例子说明了对接收信号的影响，因为信道从湍流到冻结模型的变化。
The second-order statistics of transionospheric RF scintillation are described by the two position, two-frequency, two-time mutual coherence function of the received signal. The derivation of the mutual coherence function from Maxwell's equations requires a model for the temporal and spatial variations of the electron density fluctuations in the ionosphere. Under Taylor's frozen-in hypothesis the electron density fluctuations are described as a rigid structure that drifts past the line of sight. There is then a deterministic relationship between spatial and temporal fluctuations in the electron density. This model is accurate when the ionization has formed a thin layer of striations aligned with the geomagnetic field lines. Before striations have formed or when there are multiple scattering layers in the ionosphere with different relative velocities, a turbulent model may be more appropriate. In the fully turbulent case the spatial and temporal fluctuations of the electron density are uncorrelated. Reality should lie somewhere between these two limiting models. This paper describes a general model which varies smoothly between the frozen-in and turbulent models. Examples are given which illustrate the effects on the received signal as the channel varies from the turbulent to frozen-in models.