## 4 Discussion  
This work aimed to assess the human exposure to the RF-EMFs emitted by a wearable antenna since, in recent year, we have been witnessing a growth of this technology due to its wide variety of fields of application, e.g., from medical to the military one. In particular, the antenna tuned f = 2.45 GHz has been placed near to two human models, one female and one male, in different positions, mimicking their possible realistic use. Results of this study clearly show that for both human models and in all antennas positionings, the region with higher SAR\({}_{10\text{g}}\) values are mainly located in a surface area immediately below the antenna itself and the SAR\({}_{10\text{g}}\) distributions are narrowed around their peak value. When the wearable antennas were positioned on the top of the head the SAR\({}_{10\text{g}}\) values obtained were extremely lower than all the other positions because this is the only scenario in which a medium (steel helmet) was interposed between the source and the user so the helmet shields the head of the human being, strongly reducing the interactions between the radiation and the human tissues and therefore also the contribution of the power that would otherwise have been absorbed by them. In order to deepen the incidence of the presence of a metallic medium that could shield the EMF reducing the impact on the human tissues, further simulations have been performed. More in details, in these simulations the steel helmet has been removed and then the SAR\({}_{10\text{g}}\) values have been compared with the values of the previous case. In Figure 5 the boxplots relative to the configurations with Duke and Ella, both without the steel helmet are reported. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Anatomical District** & **Duke** & **Ella** \\ \hline Ankle & 4.7 & 2.2 \\ Arm & 4 & 2.6 \\ Leg & 2.5 & 1.1 \\ Shoulder & 1.5 & 2 \\ Torso & 1.1 & 1.1 \\ Head & 0.01 & 1.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Percentage of SAR\({}_{10\text{g}}\) values between 90% of the peak and the peak of the distribution. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Anatomical District** & **Duke** & **Ella** \\ \cline{2-3} \multicolumn{1}{c}{} & **f = 2.45 GHz** & **f = 2.45 GHz** \\ \hline Ankle & 15.9 & 21.8 \\ Arm & 30.6 & 17.4 \\ Leg & 25.1 & 11.9 \\ Shoulder & 19.2 & 15 \\ Torso & 13.6 & 14.7 \\ Head & 0.0001 & 0.0001 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: SAR\({}_{10\text{g}}\) values extracted from the different exposure configurations [W/kg/W]. The results reported in Figure 5 clearly show an increase of the values of SAR\({}_{10g}\) if compared with the data obtained in presence of the helmet. This trend demonstrates that the presence of a metallic medium influences the radiation pattern of the antenna and, consequently, also the human exposure. However, the values in absence of the helmet are lower than the values from all the other configurations and the reason is the distance between the antenna and the human model; indeed, in these simulations without the helmet, the antenna is more distant than the previous configurations. Among all the other different positions of the wearable antennas here analyzed, the highest exposure values were found when the antenna was posed on the arm in the Duke model, while for Ella model, the highest peak SAR\({}_{10g}\) has been obtained when the antenna was positioned on the ankle. Excluding the antenna position close to the head, for Duke model the lowest value of peak SAR\({}_{10g}\) was obtained when the antenna was placed on the torso at the height of the heart, while for the Ella model the lowest value of peak SAR\({}_{10g}\) has been obtained when the antenna was posed on the leg. Furthermore, it can be noted that the values of the SAR\({}_{10g}\) are quite similar between Ella and Duke models when the antenna was posed close to the ankle.