# UAV Communication Recovery under Meteorological Conditions
## 3 Methods
### UAV Coverage Radius with Elevation Angle under Different Weather Conditions
At the same time, we summarize the percentage reductions in the maximum coverage radius for Regions 2 to 3 under snow, fog, and rain conditions relative to Region 1 in Table 7. Based on the data in this table, we find that under various weather conditions, relative to Region 1, the percentage reduction in the maximum coverage radius of Region 2 to Region 4 increases gradually, and the extent of each increase is approximately 10%. In addition, the difference caused by different frequencies in the percentage reduction in the coverage radius is very small. Figure 6: UAV coverage radius versus elevation angle under different weather conditions in four regions. Figure 7: Propagation attenuation under different weather conditions. small, and the coverage radius reduction percentage at 71 GHz is approximately 1% smaller than that at 28 GHz in Table 7. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Regions** & **Weather** & **28 GHz** & **71 GHz** \\ \hline \multirow{3}{*}{Region 1} & snow & 0.24\% & 2.52\% \\ \cline{2-4}  & fog & 2.49\% & 3.51\% \\ \cline{2-4}  & rain & 8.68\% & 9.55\% \\ \hline \multirow{3}{*}{Region 2} & snow & 0.21\% & 2.20\% \\ \cline{2-4}  & fog & 2.11\% & 3.00\% \\ \cline{2-4}  & rain & 7.52\% & 8.28\% \\ \hline \multirow{3}{*}{Region 3} & snow & 0.16\% & 1.80\% \\ \cline{2-4}  & fog & 1.77\% & 2.51\% \\ \cline{2-4}  & rain & 6.30\% & 7.01\% \\ \hline \multirow{3}{*}{Region 4} & snow & 0.14\% & 1.52\% \\ \cline{2-4}  & fog & 1.51\% & 2.10\% \\ \cline{2-4}  & rain & 5.46\% & 5.95\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Percentage reduction in maximum coverage radius for different weather conditions relative to atmospheric conditions. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Regions** & **Weather** & **28 GHz** & **71 GHz** \\ \hline \multirow{3}{*}{Region 1} & gas & 333.1 & 130.9 \\ \cline{2-4}  & snow & 332.3 & 127.6 \\ \cline{2-4}  & fog & 324.8 & 126.3 \\ \cline{2-4}  & rain & 304.2 & 118.4 \\ \hline \multirow{3}{*}{Region 2} & gas & 288.7 & 113.5 \\ \cline{2-4}  & snow & 288.1 & 111.0 \\ \cline{2-4}  & fog & 282.6 & 110.1 \\ \cline{2-4}  & rain & 267.0 & 104.1 \\ \hline \multirow{3}{*}{Region 3} & gas & 253.8 & 99.8 \\ \cline{2-4}  & snow & 253.4 & 98.0 \\ \cline{2-4}  & fog & 249.3 & 97.3 \\ \cline{2-4}  & rain & 237.8 & 92.8 \\ \hline \multirow{3}{*}{Region 4} & gas & 218.0 & 85.7 \\ \cline{2-4}  & snow & 217.7 & 84.4 \\ \cline{1-1} \cline{2-4}  & fog & 214.7 & 83.9 \\ \cline{1-1} \cline{2-4}  & rain & 206.1 & 80.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The maximum coverage radius (in m) of the UAV under different weather conditions in the four regions. It is worth noting that for each weather condition and frequency, there is a maximum UAV coverage radius at a certain elevation angle, which we refer to as the optimal elevation angle. The height of the UAV also becomes the optimal height at this angle. Specifically, for rain, the maximum UAV coverage radius can be found for each rainfall rate (\(R_{\rm rain}\)), as well as the corresponding UAV optimal elevation angle and optimal height. Similarly, for fog and snow, the maximum UAV coverage radius can be found for each liquid water density (\(R_{\rm fog}\)) and each snowfall rate (\(R_{\rm snow}\)). In the next subsection, we discuss the impacts of the rainfall rate, liquid water density, and snowfall rate on various aspects of UAV-ground communications. The Impacts of \(R_{\rm rain}\), \(R_{\rm fog}\), and \(R_{\rm snow}\) on UAV-Ground Communications  
In this subsection, we analyze the influence of the rainfall rate, liquid water density, and snowfall rate on the maximum coverage area and the optimal height of the UAV, respectively. Then, we introduce the concept of compensated path loss and give its calculation method. The subsection is divided into three parts.