## 8 Existing Applications of RF-EH
A textile dual-band, dual-mode antenna was introduced for simultaneous wireless information and power transfer (SWIPT) applications, which was considered the first multiband microstrip antenna with an MN-less codesigned rectenna RF-EH application [189]. As shown in Figure 9, the radio frequency identification (RFID) augmented module for smart environmental sensing (RAMSES) was first introduced in [190] as a fully passive device with sensing and computation capabilities to investigate novel and unconventional RFID applications. Table 2 lists the comparative study on the variation of existing circuits for the RF-EH approach. Figure 8: Fabricated prototype of the suggested rectenna [184]. Figure 9: RAMSES Prototype [190]. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Ref. ** & \begin{tabular}{c} **Frequency** \\ **(GHz)** \\ \end{tabular}  & \begin{tabular}{c} **Max** \\ **Conversion** \\ **(cm/m)** \\ \end{tabular}  & \begin{tabular}{c} **Circuit Size** \\ **(mm)** \\ \end{tabular}  & \begin{tabular}{c} **Max Gain** \\ **(dBm)** \\ \end{tabular}  & \begin{tabular}{c} **Max Harvested** \\ **(dBm)** \\ \end{tabular}  & \ \begin{tabular}{c} **Substrate** \\ **(dBi)** \\ \end{tabular}  & \begin{tabular}{c} **Distance** \\ **Voltage (v)** \\ \end{tabular}  & **Diode Type** \\ \hline
[173] & 24 & 80 & 40 \(\times\)40 \(\times\)1.6 & 49 & 7.8 & 6.82 & FR-4 & 1.5 & \begin{tabular}{c} Schothy \\ CMOS \\ HSIAS-2852 \\ Schottky \\ \end{tabular}  \\
[174] & 2.45 & 20 & 249 \(\times\) 8.6 \(\times\) 1.6 & \(-\)20 & 0.8 & 0.097 & FR-4 & 0.9 & \begin{tabular}{c} Schothy \\ 1.0591.5 m \\ \end{tabular}  \\
[175] & 2.45 & - & 160 \(\times\) 130 \(\times\) 0.55 & \(-\)40 to 0 & 5 & 1.0591.5 m & \ \begin{tabular}{c} Condura fabric \\ 162 m \\ \end{tabular}  & \begin{tabular}{c} 2 Schothy \\ - \\ \end{tabular}  \\
[176] & 3.1-8 & 69 & 6.3 \(\times\) 13 \(\times\) 0.8 & \(-\)10 & 3.2 & - & FR-4 & 0.5 & \begin{tabular}{c} Schothy \\ - \\ \end{tabular}  \\
[177] & 1.975-4744 & 88.58 & 40 \(\times\) 45 \(\times\) 1.6 & 0 & 4.3 & 10.703 & FR-4 & 2 & \begin{tabular}{c} HSIAS 2708 \\ Schottky \\ \end{tabular}  \\
[178] & 0.91-2.55 & 68 & 165 \(\times\) 165 \(\times\) 0.8 & \(-\)10 & 5 to 8.3 & 0.243 & FR-4 & - & HSIAS-2855 \\
[179] & 1.7-3 & 60 & 178 \(\times\) 148 \(\times\) 0.813 & - & 9.902 & -3.7 & Roger & 0.75 & SMS7630 \\
[180] & 2.4 & 50 & 637 \(\times\) 45.6 \(\times\) 1.6 & \(-\)10 \(\times\) 17 & 5.3 & 3 & FR-4 & 1-2.5 & \begin{tabular}{c} HSIAS 2850 and \\ SMS7630 \\ \end{tabular}  \\
[181] & 2.1 \& 3.3 & 76.3 & 31 \(\times\) 18 \(\times\) 1 & 4 to 16 & - & - & F4B & - & \begin{tabular}{c} HSIAS 2850 and \\ SMS7630 \\ \end{tabular}  \\
[182] & 2.4 & 69.3 & 4 \(\times\) 11.7 \(\times\) 1.6 & 5.2 & 5.9 & 3.5 & RO400 XC & - & SMS7630 \\
[183]  
Besides, as examined and verified in [191], the metamaterial absorber (MA) can be used for energy harvesting with a large fractional bandwidth (FBW). Researchers compared several substrate materials and fabrication procedures to examine micromachined antenna performance at 5 GHz for radio frequency energy harvesting (RF-EH) applications [192], as well as microwave applications [193; 194; 195].