## 3 Results and Discussion
### Specific Absorption Rate (SAR)  
The electromagnetic waves may pose a health risk to humans, and these hazards are determined by means of Sthe AR. The following is the relation between the input power and SAR [7; 8; 9; 10]:  
\[\text{SAR}=\frac{\sigma|E^{2}|}{\rho} \tag{3}\]  
The electric power intensity is proportional to the signal power, as given in the Equation (4) [10], where '\(\sigma\)' and '\(\rho\)' are electric conductivity (S/m) and mass density (kg/m\({}^{3}\)), respectively, and \(E\) is the electric field intensity (V/m).  
\[P=\frac{\left(E(\text{V/m})\right)^{2}}{377} \tag{4}\]  
Figure 11: Simulated and measured gain and radiation efficiency inside skin.  
Figure 10: Simulation and measurement far field results at 915 MHz inside the skin-gel.  
The SAR is calculated according to the IEEE/IEC 6270-1 standard, averaged across 1 g of mass tissue, with the input power '\(P_{in}\)' held stable at 0.5 W. As shown in Figure 12, the SAR values inside the skin were 8.22 W/kg at 915 MHz.  
The proposed design is compared to the state-of the art in the literature in Table 2. From the table, the proposed design is smaller in size and achieved a much wider bandwidth and much lower value of the specific absorption rate (SAR) than the other reported designs in the literature.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Ref. No.**} & **Dimensions** & **Operating** & **Realized** & **Operating** & **SAR** \\  & \(\left(\mathbf{mm^{3}}\right)/\left(\lambda_{g}\mathbf{{}^{3}}\right)\) & **Frequency** & **Gain** & **Bandwidth** & **(W/kg)** \\ \hline
[10] &
\begin{tabular}{c} (23 \(\times\) 16.4 \(\times\) 1.27) \\ (0.098 \(\times\) 0.070 \(\times\) 0.005) \\ \end{tabular} & 0.402 & \(-\)34.9 & 12.9 & 284.5 \\ \hline
[11] &
\begin{tabular}{c} (25 \(\times\) 20 \(\times\) 0.07) \\ (0.34 \(\times\) 0.27 \(\times\) 0.00095) \\ \end{tabular} & 2.45 & \(-\)16.8 & 1.22 & 1.0 \\ \hline
[12] & \
\begin{tabular}{c} (15 \(\times\) 21.5 \(\times\) 1.5748) \\ (0.39 \(\times\) 0.56 \(\times\) 0.039) \\ \end{tabular} & 2.45 & \(<\)\(-\)15 & 3.2 &
\begin{tabular}{c} Not \\ Calculated \\ \end{tabular} \\ \hline
[13] & \
\begin{tabular}{c} (3.14 \(\times\) 100 \(\times\) 2.54) \\ (0.082 \(\times\) 2.6 \(\times\) 0.066) \\ \end{tabular} & 0.4/ & \(-\)33.1/ & 38.1/ 17.6 &
\begin{tabular}{c} 241.5/ \\ 149.7 \\ \end{tabular} \\ \hline
[15] &
\begin{tabular}{c} (14 \(\times\) 14 \(\times\) 0.5) \\ (0.365 \(\times\) 0.365 \(\times\) 0.013) \\ \end{tabular} & 2.45 & \(-\)15.96 & 18.36 & 0.494 \\ \hline
[17] & \
\begin{tabular}{c} (3.14 \(\times\) 28.6 \(\times\) 1.34) \\ (0.082 \(\times\) 0.748 \(\times\) 0.035) \\ \end{tabular} & 0.402/ & \(-\)41/ & 41/ 27.8 &
\begin{tabular}{c} 666/ \\ 676 \\ \end{tabular} \\ \hline
[18] &
\begin{tabular}{c} (3.14 \(\times\) 23 \(\times\) 0.634) \\ (0.082 \(\times\) 0.60 \(\times\) 0.016) \\ \end{tabular} & 2.45 & \(-\)20.3 & 18.3 & 649 \\ \hline
[19] & \
\begin{tabular}{c} \(11\times\) 11 \(\times\) 1.27 \\ (0.107 \(\times\) 0.107 \(\times\) 0.0123) \\ \end{tabular} & 0.915 & \(-\)29 & 3.8 &
\begin{tabular}{c} Not \\ Calculated \\ \end{tabular} \\ \hline
[20] &
\begin{tabular}{c} \(15\times\) 15 \(\times\) 1.27 \\ (0.14 \(\times\) 0.14 \(\times\) 0.0123) \\ \end{tabular} & 0.915 & \(-\)27 & 10.6 & 517 \\ \hline
[21] &
\begin{tabular}{c} 3.14 \(\times\) 22.09 \(\times\) 1.27 \\ (0.030 \(\times\) 0.22 \(\times\) 0.0123) \\ \end{tabular} & 0.915 & \(-\)32.8 & 12.2 & 778 \\ \hline
[This work] &
\begin{tabular}{c} **7 \(\times\) 7 \(\times\) 0.254** \\ **(0.027 \(\times\) 0.027 \(\times\) 0.0011)** \\ \end{tabular} & **0.915** & \(-\)**28** & **25.13** & **8.22** \\ \hline \hline \end{tabular}
\end{table}
Table 2: A comparison of the proposed antenna’s performance to that of recent work.  
Figure 12: At 915 MHz, SAR distribution of the specified antenna inside the skin tissue over 1 g.