## 4 Results and Discussion  
The prototype WPT circuit included two copper coils of 28 AWG magnetic wire, because 28 AWG is more efficient regarding the transfer of power than 22 AWG with a higher inductance value (Table 2). A voltage regulator component to control the required voltage passed to the mobile device battery for charging with 5 V to initiate the charging process, as depicted in Figure 6. The purpose of a voltage regulator was to normalize the voltage levels. The voltage regulator steps down the input voltage to the anticipated level and preserves it at a similar level during the supply. This ensures that even when a load is applied, the voltage does not drop.  
The voltage (1.142 V) initially acquired from the RF energy harvesting circuit [30] was too limited for charging the battery of a mobile device. Transferring the power wirelessly would result in some voltage being lost. The RF energy harvesting process with WPT, as shown in Figure 6, is summarized as follows. A capacitor (100 \(\mu\)F, 16 V) was later included in the RF energy harvesting circuit to store the converted power [30]. Referring to the simulated tests, 6 V was the estimated input voltage to initiate the charging process. Compared with the experimental results, the RF energy harvested power exceeded that value and provided 9.46 V to the magnetically coupled circuit for the wireless power transfer to the load for charging. The capacitor was connected to the RF harvesting circuit for 7.5 h. The accumulated voltage stored in the capacitor was 9.46 V. Taking into consideration the average voltage (6.03 V) flowing through the circuit, this was sufficient for the charging of the mobile device battery. An additional capacitor with the stored charge after rectification (conversion of AC to DC) was connected to the WPT charging circuit. This was sufficient to commence the charging of the battery of a mobile device through the wireless power transfer and in the event of voltage loss across the air gap. It can be concluded based on the results discussed in this research paper that WPT as an alternative form of energy is possible and is readily available for charging the batteries of mobile devices wirelessly. It can be concluded that the higher the harvested energy, the more effective the charging process of the battery of a mobile device.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**AWG Wire** & **Wire Diameter (mm)** & **Loop Diameter (mm)** & **Relative Permeability** & **Inductance (H)** \\ \hline
21 & 0.7239 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 1.70 \(\times\) 10\({}^{-13}\) \\ \hline
22 & 0.6438 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 1.75 \(\times\) 10\({}^{-13}\) \\ \hline
24 & 0.5106 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 1.83 \(\times\) 10\({}^{-13}\) \\ \hline
26 & 0.4038 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 1.93 \(\times\) 10\({}^{13}\) \\ \hline
27 & 0.3606 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 1.98 \(\times\) 10\({}^{-13}\) \\ \hline
28 & 0.3211 & 50 & 1.256 \(\times\) 10\({}^{-6}\) & 2.02 \(\times\) 10\({}^{-13}\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: AWG wire inductance comparison [39].  
Figure 6: (**a**) Prototype circuit with the voltage rectifier connected to the coils. (**b**) MRC circuit connected to the voltage regulator. (**c**) MRC coils with the voltage rectifier component.