## 3 Development and Experimentation  
This article contains the data of the experimental measurements, where the measurements were carried out both with a winged and fixed-wing aircraft. The Ukmerge city (Lithuania) television broadcasting tower (Figure 8) was selected for the experiment, as one of the towers whose real antenna diagram is of interest to the Communications Regulatory Service in Lithuania. Figure 6: **(a)** The mounting of measurement antennas in the aircraft. **(b)** The launch of the aircraft. Figure 7: **(a)** Ground station and software for data collection and analysis. **(b)** Ground station and software for the aircraft control. The GPS coordinates of the telecommunication tower are latitude N55.2280555555555 and longitude E24.8266666666666666. The height of the area above sea level is 136 m. The height of the center of the antenna is 103 m above the ground and 239 m above sea level. Broadcast channels: 29 (538 MHz) and 32 (562 MHz), polarization H. Theoretical (declared broadcast antenna data, Table 1): Broadcast antenna Kathrein 770 881. Channels 29 and 32 were selected for the analysis of the broadcast antenna, Kathrein 770 881. During the measurements, a real-time spectrum analyzer, BB60C, connected to a Raspberry Pi Foundation developed Raspberry Pi embedded computer was used. The embedded computer was connected to a digital data transmission system, allowing remote monitoring and control of the measurements. Specialized spectrum analyzer software was developed, to collect and transmit data to a ground station separate from the UAV control, as shown in Figure 7a. Since the measurement data were recorded at each measurement moment (approximately every 1 s) in different spatial positions, due to the flight characteristics of the UAVs, a new data processing and visualization algorithm had to be developed (see Figure 9): \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Azimuth in** & \multirow{2}{*}{**Antenna Gain, dB**} & **Azimuth in the Horizontal Plane, in Degree** & \multirow{2}{*}{**Antenna Gain, dB**} & **Azimuth in the Gain, dB** & & **Azimuth in the Horizontal Plane, in Degree** & \multirow{2}{*}{**Antenna Gain, dB**} \\ \hline
0 & 8 & 90 & 8 & 180 & 8 & 270 & 8 \\
10 & 7.7 & 100 & 7.7 & 190 & 7.7 & 280 & 7.7 \\
20 & 7 & 110 & 7 & 200 & 7 & 290 & 7 \\
30 & 5.7 & 120 & 5.7 & 210 & 5.7 & 300 & 5.7 \\
40 & 5 & 130 & 5 & 220 & 5 & 310 & 5 \\
50 & 5 & 140 & 5 & 230 & 5 & 320 & 5 \\
60 & 5.7 & 150 & 5.7 & 240 & 5.7 & 330 & 5.7 \\
70 & 6.5 & 160 & 6.5 & 250 & 6.5 & 340 & 6.5 \\
80 & 7.7 & 170 & 7.7 & 260 & 7.7 & 350 & 7.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Theoretical Kathrein 770 881 antenna data. Figure 8: Ukmerge city telecommunication broadcasting tower. Figure 9: Algorithm for data collection, analysis, and visualization. The algorithm first takes the collected data and plots coordinate points in three-dimensional space, creating a flight map where each point stores the measurement result. In data analysis, possible random measurement errors are additionally evaluated, and potentially incorrect values are eliminated. Since the flight altitude and distance vary, the algorithm allows the assigning of measurement results according to the desired height and distance from the antenna. In the final step, the algorithm, as developed by the authors, can calculate the average electromagnetic field strength in dB values in the desired area or visualize the strength in space with colors depending on the measured instantaneous electromagnetic field strength. An example of a flight trajectory and the corresponding measured values in three-dimensional space is presented in Appendix A. Our algorithm is unique because, unlike the reviewed works that mainly focused on image processing or simple classification tasks, it combines real-time drone flights with GPS-coordinated measurements of electromagnetic fields around telecommunication towers.