## 2 Methodology
### Dataset
Beamforming adjusts the radiation direction of antennas, concentrating wireless signals in a specific direction rather than radiating them uniformly, which results in a higher gain value for the antenna. Just as the distance (D) between the 5G base station and the measurement site influences the measured electric field intensity, D is also selected as an input parameter. A higher observed electric field intensity results from multiple beam overlaps caused by a concentration of 5G terminals. Therefore, we believe that the number of terminals has a significant impact on the detected radiation level from the 5G base station. In the measurement, we increase the number of 5G terminals from 1 to 4 to represent a more typical scenario. By analyzing monitoring data from selected areas in Lagos, Nigeria, we observe that as the number of terminals increases, the monitoring field strength also rises (Table 4). Given its importance to the outcome, the number of terminals is one of the key features included in our model. In practice, the antenna transmit power varies as the terminal service modes change. Therefore, it is important to consider both the impact of terminal service modes on transmit power and the effect of antenna transmit power on the level of electromagnetic radiation. An analysis of monitoring data from selected areas in Lagos reveals that the electric field \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Number of Terminal**} & \multirow{2}{*}{**Station 1 (Lekki Region)**} & \multicolumn{2}{c}{**Station 2**} & \multirow{2}{*}{**Station 3 (Ajah Region)**} \\  & & **(Lagos Island Region)** & \\ \hline
1 & 0.998 & 0.474 & 0.196 \\ \hline
2 & 1.014 & 1.896 & 1.546 \\ \hline
4 & 2.411 & 4.477 & 4.354 \\ \hline \hline \end{tabular} Measurements are in V/m.  
\end{table} 
Table 4: The intensity of the electric field increases as the number of terminals increases. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Site**} & \multicolumn{1}{c}{**Base Station**} & \multicolumn{1}{c}{**Gain (dBi)**} & \multicolumn{1}{c}{**Transmission Power (W)**} \\ \hline
1 & BTS5A23 & 23.46 & 221 \\ \hline
2 & A9921B X28 & 17.93 & 250 \\ \hline
3 & BS6712 & 24.47 & 125 \\ \hline
4 & BTS6C22 & 17.93 & 339 \\ \hline
5 & A9941B X28 & 23.46 & 221 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Transmission power at various locations. intensity changes with different terminal service modes (Table 5). The data transmission mode results in significantly higher electric field intensity compared to voice communication, with different service modes corresponding to varying data transmission rates (Table 6). As a result, we have included the 5G terminal service mode (TSM) as a feature in our model. Data for our model was collected from 52 base stations across various regions of Lagos, Nigeria. These base stations are situated in diverse environments, ranging from busy streets to remote suburbs. To account for the potential reflections and diffractions caused by nearby buildings on test site results, we included environmental variables as inputs, considering both line-of-sight (LOS) and non-line-of-sight (NLOS) transmission scenarios. Consequently, the complex surrounding environment of each 5G base station (C) became a key characteristic. Lagos, Nigeria, experiences two primary seasons: the wet and dry seasons. Prior studies [32; 33] have shown that atmospheric refractivity is higher during the wet season compared to the dry season, making the wet season the worse atmospheric period for analysis. Therefore, the RF measurement campaign was conducted in August 2024, at the height of the rainy season, to capture the effects of atmospheric attenuation. The height of the base station is 60 m according to the service providers, while the height of the receiving station is maintained at 1 m throughout. The measurements were taken at a distance ranging from 0.5 m to 3 m away from the base station.