Faculty of Engineering, Ariel University, Ariel 40700, Israel.
Sensors (Basel). 2018 Jul 4;18(7):2148. doi: 10.3390/s18072148.
Attenuation and group delay effects on millimeter wave (MMW) propagation in clouds and fog are studied theoretically and verified experimentally using high resolution radar in an indoor space filled with artificial fog. In the theoretical analysis, the frequency-dependent attenuation and group delay were derived via the permittivity of the medium. The results are applied to modify the millimeter-wave propagation model (MPM) and employed to study the effect of fog and cloud on the accuracy of the Frequency-Modulated Continuous-Wave (FMCW) radar operating in millimeter wavelengths. Artificial fog was generated in the experimental study to demonstrate ultra-low visibility in a confined space. The resulted attenuation and group delay were measured using FMCW radar operating at 320⁻330 GHz. It was found that apart from the attenuation, the incremental group delay caused by the fog also played a role in the accuracy of the radar. The results were compared to the analytical model. It was shown that although the artificial fog has slight different characteristics compare to the natural fog and clouds, in particle composition, size, and density, the model predictions were good, pointing out that the dispersive effects should be considered in the design of remote sensing radars operating in millimeter and sub-millimeter wavelengths.
衰减和群延迟对毫米波（MMW）在云和雾中的传播的影响在理论上进行了研究，并在充满人工雾的室内空间中使用高分辨率雷达进行了实验验证。在理论分析中，通过介质的介电常数推导出频率相关的衰减和群延迟。这些结果被应用于修正毫米波传播模型（MPM），并用于研究雾和云对在毫米波工作的调频连续波（FMCW）雷达精度的影响。在实验研究中产生了人工雾，以证明在封闭空间中的超低能见度。使用在 320-330GHz 工作的 FMCW 雷达测量得到的衰减和群延迟。结果表明，除了衰减之外，雾引起的增量群延迟也会影响雷达的精度。结果与分析模型进行了比较。结果表明，尽管人工雾在颗粒组成、大小和密度方面与天然雾和云略有不同，但模型预测效果良好，指出在设计在毫米和亚毫米波段工作的遥感雷达时应考虑色散效应。
