# The Impact of an Electric Machine Body on EM Wave Propagation in RTMS
## 4 Experimental Results  
In this section, we will validate the simulations discussed earlier in the paper. We conducted experiments on a single-phase squirrel cage asynchronous machine using two RN-171 antennas introduced in Section 3.3. Figure 6 shows the placement of the RN-171 transmitter inside the electrical machine. The propagation factor within the electrical machine was 0.3 \(\times\) 10\({}^{-5}\), closely matching the simulated values. The two antennas were arranged similarly to previous simulations, approximating the maximum free-space over-ground propagation factor. Despite the antennas not being optimized for their surroundings, the power transfer efficiency was higher than theoretical predictions for two comparable antennas in a free-space scenario. Our research focused on the effect of antenna positioning, specifically using the RN-171 transmitter, on the computed propagation factor. Interestingly, our analysis showed a significant decrease in the propagation factor when the antenna was placed on the machine \begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameter Name** & **Open Space** & **Carcass, Stator, Rotor and Shaft** \\ \hline \(\left|S_{11}\right|\) & 0.08456 & 0.09124 \\ \(\left|S_{21}\right|\) & 0.01524 & 0.00145 \\ \(\left|S_{22}\right|\) & 0.09235 & 0.0823 \\ \(\left|F_{p}\right.\)(10\({}^{-5}\))\(\left|\right.\) & 23.13 & 0.209 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: \(F_{p}\) for two RN-171 antennas. Figure 6: RN171 antenna mounted inside the electrical machine. compared to its performance in free space. This reduction aligns with theoretical expectations, as obstructions within the electrical machine significantly impact electromagnetic wave propagation. The introduction of electrical components adds complexity and leads to signal attenuation. A major factor in this is interference from electrical noise, which greatly impairs wave propagation within the machine. These observations highlight the complex interaction between the machine's electromagnetic environment and wave behavior. This insight provides important considerations for future applications and improvements in industrial settings. Table 3 presents an analysis of monopole antennas versus other types of antennas based on five different research works. This comparison includes evaluation parameters such as radiation patterns, gain, bandwidth, efficiency, size, ease of integration, and propagation factors. The aim is to highlight the performance characteristics and practical benefits of monopole antennas in various communication scenarios. Monopole antennas offer advantages in terms of omnidirectional coverage, compact size, ease of integration, and consistent performance across varied environments. They are suitable for applications requiring uniform coverage and reliable performance in different orientations and settings. While other antennas like dipole, patch, loop, helical, and YagiUda antennas provide specific benefits in terms of gain, bandwidth, and directivity, the practical benefits of monopole antennas make them a preferred choice for many modern wireless communication applications.