宽带高频天波传播：综述与传播数据验证的链路建模
Wideband HF Skywave Propagation: A Review with Link Modeling Corroborated by Propagation Data
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中文总结 AI 辅助
本文综述宽带高频天波通信的挑战，通过射线追踪建模NVIS和远距离链路，并用FT8数据和电离图验证，强调高方向性天线和噪声模型的作用。
中文摘要 AI 辅助
高频（HF）频段，范围从3到30 MHz，广泛应用于超视距（BLOS）通信和超视距雷达系统等众多应用中。高频频段的远距离传播特性依赖于地球电离层作为折射介质来建立超视距无线链路。然而，传统的高频通信链路通常使用窄带宽信道（典型为3 kHz），这限制了可传输的数据量。在这篇观点文章中，我们讨论了建立宽带高频通信链路的挑战，重点涉及电离层、噪声特性、天线性能和可用带宽。太阳辐射驱动电离层分层，其中波动的电子密度决定了可用频率，这些频率随一天中的时间、季节和纬度而变化。由于高频下的背景噪声随频率增加而降低，因此在较高高频极限下工作是有利的。我们提出了一个遵循ITU建议P.372-17的噪声预测模型，并强调了高方向性天线（如对数周期偶极子阵列）在优化链路信噪比中的作用。利用射线追踪技术，我们模拟了几条代表性的宽带高频链路，这些链路采用近垂直入射天波（NVIS）或远距离天波模式，距离范围从约390到5,200公里。我们检查了这些链路在高达1 MHz带宽下的性能，并展示了它们的白天和夜间电离图，发射机和接收机位置从近赤道到高北纬度。对于有传播数据可用的链路，我们将建模的最大可用频率与同期众包FT8接收数据和直接电离层探测测量进行了验证。
英文摘要
The high-frequency (HF) band, ranging from 3 to 30 MHz, is widely used in a number of applications such as beyond-line-of-sight (BLOS) communications and over-the-horizon radar systems. The long-range propagation characteristics of the HF band rely on the Earth's ionosphere as a refracting medium to establish BLOS wireless links. However, traditional HF communications links often use channels with narrow bandwidths (typically 3 kHz), which limits the amount of data that can be transmitted. In this perspective article, we discuss the challenges of establishing wideband HF communications links with emphasis on the ionosphere, noise characteristics, antenna performance, and available bandwidth. Solar radiation drives ionospheric layering, where fluctuating electron densities determine usable frequencies that change with time of day, seasons, and latitude. Since background noise at HF decreases with increasing frequency, operating at the upper HF limit is advantageous. We present a noise prediction model following ITU Recommendation P.372-17 and highlight the role of high-directivity antennas such as Log-Periodic Dipole Arrays, in optimizing the signal-to-noise ratio of the link. Using ray tracing techniques, we model several representative wideband HF links that employ near-vertical-incidence skywave (NVIS) or long-range skywave modes over distances ranging from approximately 390 to 5,200 km. We examine the performance of these links for bandwidths up to 1 MHz and present their day and night ionograms, with transmitter and receiver locations spanning near-equatorial to high northern latitudes. The modeled maximum usable frequencies are corroborated against crowdsourced FT8 reception data and direct ionosonde measurements over the same period for links for which propagation data was available.
发表机构
- University of Wisconsin-Madison（威斯康星大学麦迪逊分校）
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