# A Compact Circular Rectenna for RF-Energy Harvesting at ISM Band
## 5 Conclusions  
In this work, a CMCP monopole antenna has been reported for surrounding RF-energy harvesting at ISM band. The proposed antenna is optimized to 50 \(\Omega\) impedance at the operating frequency using a partial ground plane. The results show an approximate omnidirectional radiation pattern in both E-plane and H-plane with a gain of 2.38 dBi at 2.45 GHz. Moreover, a simple efficient rectifier with L-section IMN is designed and its performance is analyzed at 2.45 GHz. The rectenna is fabricated and tested at 2.45 GHz and the measured results demonstrate that the proposed rectifier network provides 2.17 V and 0.48 mW of output DC voltage and power, respectively, with a 52% rectifier efficiency at a small input RF power of 0 dBm. This describes the potential of the rectifier to collect ambient RF power and convert it into usable DC power, resulting in a fabricated prototype rectenna model that is apt for powering low sensor applications, making them sustainable, and for the model's use in wireless sensor network applications. Future aspects that are recommended to be further explored include the design of a multiband rectenna and to evaluate the multistage rectifier so as to obtain more efficiency at multiple RF-input wavelengths, as well as to design a compact rectenna for on-body applications. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Reference**} & \multirow{2}{*}{\begin{tabular}{c} **Antenna Size** \\ **(mm\({}^{3}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Frequency** \\ **(GHz)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Rectifier** \\ **Type** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Input Power** \\ **(dBm)** \\ \end{tabular} } & \multirow{2}{*}{**PCE (\%)**} & \multirow{2}{*}{\
\begin{tabular}{c} **Load** \\ **Resistance (\(\Omega\))** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Output DC** \\ **Voltage (V)** \\ \end{tabular} } \\ \hline
[12] & \(135\times 93\times 1.5\) & 2.45 &
\begin{tabular}{c} Shunt and \\ series \\ \end{tabular} & 13 & 72.5 & 900 & NA * \\ \hline
[13] & \(24.9\times 8.6\times 1.6\) & 2.45 &
\begin{tabular}{c} Voltage \\ doubler \\ \end{tabular} & \(-20\) & 20 & 4.7 K & 97 m \\ \hline
[14] & \(18\times 30\times 1.6\) & 2.45 &
\begin{tabular}{c} Cockcroft- \\ Walton \\ \end{tabular} & 5 & 68 & 5 K & 3.24 \\ \hline
[15] & \(28\times 37.6\times 1.6\) & 2.42 &
\begin{tabular}{c} Voltage \\ doubler \\ \end{tabular} & 0 & 62 & 3.8 K & 1.5 \\ \hline
[17] & \(7.9\times 7.7\times 1.27\) & 0.915 &
\begin{tabular}{c} Voltage \\ doubler \\ \end{tabular} & 5 & 45 & 4.3 K & 168.3 m \\ \hline
[19] & \(110\times 90\times 0.635\) & 2.45 & \
\begin{tabular}{c} Series diode \\ doubler \\ \end{tabular} & \(-3.2\) & 83 & 1.4 K & 1.0 \\ \hline This work & \(50\times 50\times 1.6\) & 2.45 &
\begin{tabular}{c} Voltage \\ doubler \\ \end{tabular} & 0 & 52 & 10 K & 2.17 \\ \hline \hline \end{tabular}  
* Not Applicable.  
\end{table} 
Table 2: Comparison of the rectenna model in this work with the related work available in the literature. Figure 14: Comparison of simulated and measured (**a**) conversion efficiency (**b**) \(\mathrm{V_{out}}\), \(\mathrm{P_{out}}\) vs. \(\mathrm{P_{in}}\). **Author Contributions:** Conceptualization, L.P. and H.C.M. ; methodology, L.P. and H.C.M. ; software, L.P. and H.C.M. ; validation, L.P. and H.C.M. ; formal analysis, H.C.M. and H.G.M. ; investigation, L.P. and H.G.M. ; resources, L.P. and H.C.M. ; data curation, L.P. and H.C.M. ; writing--original draft preparation, L.P. and H.C.M. ; writing--review and editing, L.P., H.C.M. and H.G.M. ; visualization, L.P., H.C.M. and H.G.M. ; supervision, H.C.M. ; project administration, H.C.M. and H.G.M. ; funding acquisition, H.G.M. All authors have read and agreed to the published version of the manuscript. **Funding:** [PERSON] [PERSON] hint Abdulrahman University Researchers Supporting Project number (PNURSP2023 TR140), [PERSON] [PERSON] hint Abdulrahman University, Riyadh, Saudi Arabia.