# Exploring Carbon-Fiber UAV Structures as Communication Antennas for Adaptive Relay Applications
## 3 Results
### Propagation Models Results
These fluctuations underscore how signal phase interactions and wave propagation paths are highly sensitive to spatial changes in the environment. Figure 21 evaluates the influence of the number of holes (i.e., signal paths created) on the received power. The \(x\)-axis shows the number of open rows (holes) introduced, from 1 to 8, including the \"Nothing\" (fully covered) and \"Everything\" (all rows open) cases. The variation in received power is generally minor, staying between \(-55.5\) dBm and \(-57.5\) dBm, but there is a clear trend of increased signal fluctuation with more holes, consistent with multipath fading effects. Interestingly, opening all rows (\"Everything\") did not result  
Figure 21: Influence of the number of holes. Figure 20: Influence of the position of a hole. in the maximum loss, which indicates that signal components might partially reinforce depending on their phase. Still, setups with intermediate numbers of holes (e.g., 4 or 6) caused more significant signal drops, again illustrating that destructive interference is not necessarily proportional to the number of paths but rather their relative phase alignment. As also observed in the previous graph, Figure 17, small structural or spatial changes can lead to measurable effects in signal reception. In this case, the relative difference between the highest and lowest received power is 2.72%, emphasizing the sensitivity of the system to environmental symmetry and wave superposition. For the small-scale fading, we did the measurements outside the anechoic chamber. We placed the two antennas in the work environment next to the lab room marked by the black rectangles, Figure 22.  
We measured the received power during several different scenarios. Once we walked with several persons between the two antennas, we put two big closets between the two antennas. We also put the receiving antenna in another room to see the differences. We also moved with two metal plates between the two antennas. In the first scenario involving people, three individuals participated, all with an average height of approximately 180 cm and normal body proportions. They moved at a walking pace between the transmitting and receiving antennas, simulating realistic human movement within indoor environments. Their presence introduced dynamic obstructions, resulting in fluctuating attenuation and multipath components. In another scenario, we introduced two large wooden closets between the antennas. Each closet had dimensions of approximately 1.2 m in width and depth and 2.5 m in height. Due to their size and solid wooden construction, these objects created significant attenuation and partial signal blockage, offering insights into the effects of bulky furniture on radio propagation. The metal plates used in the experiment were square-shaped aluminum sheets, each with a side length of approximately 1.5 m. These were held and moved manually between the antennas to deliberately introduce strong reflectors into the propagation path. Due to their size and conductive nature, the plates significantly altered the signal paths by creating additional reflections and attenuation. Additionally, in one scenario, the receiving antenna was placed in an adjacent room, separated by a brick wall with a thickness of 8 cm. This barrier introduced additional attenuation and tested the ability of the signal to penetrate typical building materials. These scenarios were designed to replicate realistic indoor propagation environments, where obstacles such as people, furniture, and walls can lead to multipath effects, signal absorption, and diffraction. The goal was to observe how the received power would  
Figure 22: Test chamber array. vary under each condition, providing qualitative and quantitative insight into the signal degradation caused by environmental factors.