## 2 Antenna Configuration  
The geometry of the antenna is depicted in Figure 1. The antenna is composed of a corner-truncated patch surrounded by parasitic elements. The patch is with a cross-slot at the center. The antenna is deposited on top of a grounded single substrate layer made of felt (\(\varepsilon_{r}\) = 1.35, tan \(\delta\) = 0.03). Both the patch and the ground are made of conductive textiles with a conductivity of \(\sigma\) = 1.18 \(\times\) 10\({}^{5}\) S/m (Shieldit Super from LessEMF Inc, Latham NY, USA.). The materials are flexible so that the antenna is friendly to be worn on the body. A ground shielding topology rather than unshielded ones [6,33] is adopted to reduce the human body loading effect on the antenna performance. Since a large area is available on the body, the antenna ground can be kept large to have higher gain and less radiation exposure issues. The thickness of the felt substrate and the conductive textiles are 3 mm and 0.17 mm, respectively. This results in a low-profile structure whose thickness is only 0.027 \(\lambda_{0}\). An antenna prototype is fabricated, as shown in Figure 9a. All the materials were cut manually. The textile radiator, the ground layer, and the felt substrate were ironed together with thermal melting glue. An SMA connector was soldered to the ground and to the patch to feed the antenna for measurements using a temperature-tunable soldering iron to avoid burning the textile. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref. **} & \multirow{2}{*}{ \begin{tabular}{c} **\(f_{\theta}\)** \\ **(GHz)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Size (mm)\({}^{3}\)**,** \\ \(\lambda_{0}\times\lambda_{0}\times\lambda_{0}\) \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Impedance** \\ **BW (GHz)** \\ \end{tabular}  } & \multirow{2}{*}{**3-dB AR**} & \multirow{2}{*}{**Peak Gain**} & \multirow{2}{*}{**Efficiency**} & \multirow{2}{*}{\ \begin{tabular}{c} **FRR** \\ **(dB)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Wearable** \\ **Material** \\ \end{tabular}  } \\ \hline
[12] & 5.8 & \begin{tabular}{c} 14.1 \(\times\) 14.1 \(\times\) 10.29, \\ 0.273 \(\times\) 0.273 \(\times\) 0.199 \\ \end{tabular}  & \begin{tabular}{c} 5.68-5.91 \\ 3.97\% \\ \end{tabular}  & \begin{tabular}{c} 5.72-5.89 \\ 2.93\% \\ \end{tabular}  & \begin{tabular}{c} 2.1 dBic \\ 2.93\% \\ \end{tabular}  & \ \begin{tabular}{c} 72.6\% \\ \end{tabular}  & \begin{tabular}{c} NA \\ \end{tabular}  & Yes \\ \hline
[13] & 6 & \begin{tabular}{c} 40 \(\times\) 40 \(\times\) 4.5, \\ 0.8 \(\times\) 0.89 \(\times\) 0.020 \\ \end{tabular}  & \begin{tabular}{c} 5.0-7.0 \\ 33\% \\ \end{tabular}  & \begin{tabular}{c} 5.38-6.62 \\ 20.7\% \\ \end{tabular}  & \begin{tabular}{c} 8.6 dBic \\ 20.7\% \\ \end{tabular}  & \ \begin{tabular}{c} NA \\ \end{tabular}  & \begin{tabular}{c} 20 \({}^{*}\) \\ \end{tabular}  & No, rigid \\ \hline
[14] & 2.49 & \begin{tabular}{c} 130 \(\times\) 130 \(\times\) 15, \\ 1.079 \(\times\) 1.09 \(\times\) 0.125 \\ \end{tabular}  & \begin{tabular}{c} 1.87-3.11 \\ 49.8\% \\ \end{tabular}  & \begin{tabular}{c} 2.32-2.95 \\ 24\% \\ \end{tabular}  & \ \begin{tabular}{c} 8.7 dBic \\ 24\% \\ \end{tabular}  & NA & \begin{tabular}{c} 25 \({}^{*}\) \\ \end{tabular}  & No, rigid \\ \hline
[17] & 5.44 & \begin{tabular}{c} 40 \(\times\) 40 \(\times\) 4, \\ 0.725 \(\times\) 0.725 \(\times\) 0.072 \\ \end{tabular}  & \begin{tabular}{c} 4.25-6.63 \\ 43\% \\ \end{tabular}  & \begin{tabular}{c} 4.71-6.67 \\ 34\% \\ \end{tabular}  & \begin{tabular}{c} 7.5 dBic \\ 34\% \\ \end{tabular}  & \ \begin{tabular}{c} NA \\ \end{tabular}  & \begin{tabular}{c} 30 \({}^{*}\) \\ \end{tabular}  & Yes \\ \hline
[18] & 5.47 & \begin{tabular}{c} 54 \(\times\) 54 \(\times\) 4, \\ 0.985 \(\times\) 0.985 \(\times\) 0.880 \\ \end{tabular}  & \begin{tabular}{c} 4.51-6.43 \\ 35.15 \(\times\) 0.980 \\ \end{tabular}  & \begin{tabular}{c} 5.02-5.98 \\ 35.15 \\ \end{tabular}  & \begin{tabular}{c} 8.5 dBic \\ 17.5\% \\ \end{tabular}  & \