## 4 Results and Discussion
Dividing Equation (11) by Equation (12),  
\[\frac{P_{SG}}{P_{AUT}}=\frac{G_{SG}}{G_{AUT}} \tag{13}\]  
Converting to dB scale,  
\[P_{SG|dB}-P_{AUT|dB}=G_{SG|dB}-G_{AUT|dB} \tag{14}\]  
\[G_{AUT|dB}=G_{SG|dB}+10 log_{10}(\frac{P_{AUT|dB}}{P_{SG|dB}}) \tag{15}\]  
The measurement is taken at the far field region. \[S\geq\frac{2D^{2}}{\lambda} \tag{16}\]  
where \(D\) is the broader dimension of the antenna, and \(S\) is the minimum distance between the transmitting antenna and the receiving antenna. The radiation pattern was simulated, and measurements were carried out within an anechoic chamber. Figure 11a-e depict the simulated and measured radiation patterns at 4.02, 9.07, and 11.48 GHz. In particular, the E-plane radiation patterns, as seen in the measured data, closely align with the simulation results, exhibiting a figure-of-eight shape indicative of a robust bidirectional pattern. Conversely, the H-plane pattern appears to be nearly omnidirectional. Overall, the measured E-plane pattern more closely mirrors the simulated pattern compared to the H-plane pattern. It is worth noting that the measured curves display numerous ripples and distortions, likely stemming from factors such as soldering residue, feed connectors, fabrication, and assembly errors. The simulated and measured parameters of the CMFA are presented in Figure 7:0 It can be seen that there is a noticeable enhancement in the antenna's fractional bandwidth from the measured result. Figure 7:1 _Cont._ \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Simulated** & **Measured** \\ \hline Highest Frequency (_Hf_) & 12.45 & 13.6 \\ Lowest Frequency (_Lf_) & 3.17 & 3.37 \\ Operating Band & 3.17–12.45 & 3.37–13.6 \\ Fractional Bandwidth & 118.7\% & 120.6\% \\ Min. Ref. Coef. & \(-\)34.71 & \(-\)40.03 \\ \hline \hline \end{tabular} Note: Frequency in GHz, Minimum Reflection Coefficient (Min. Ref Coef.) in dB.  
\end{table} 
Table 1: Summary of the simulated and measured parameters of the CMFA. Figure 10: Fabricated CMFA: (**a**) front view of the prototype, (**b**) back view of the prototype, (**c**) receiver, (**d**) transmitter, and (**e**) reflection coefficient measurement setup. Figure 12 shows the surface current distribution on the CMFA; it can be seen that different frequencies show different patterns in the surface current. When the frequency is set to 4.02 GHz, it is more pronounced in the patch's central arc slot and along the lower edge of the radiating patch. The surface current also becomes more prominent at 9.7 GHz along the radiating patch's upper corner and bottom edge. Finally, at 11.48 GHz, the surface current significantly increases along the radiating patch's lower edge and arc-shaped slots, resulting in a variety of behaviors at various frequencies. The interactions between electromagnetic waves and the radiating patch's shape at the relevant frequencies are thought to be the cause of these events. At 4.02 GHz, the surface current is more noticeable along the bottom edge and the central arc slot of the radiating patch due to the resonance effects created by the geometry of the patch at that frequency. Similarly, at 9.7 GHz, the surface current becomes more prominent along the lower edge and upper corner of the patch due to the specific dimensions and layout of the patch, which resonate with the electromagnetic waves at that frequency. Lastly, at 11.48 GHz, the notable increase in surface current along the lower edge and arc-shaped slots can be attributed to another resonance effect caused by the interaction between the electromagnetic waves and the intricate features of the patch. In essence, the geometry and layout of the radiating patch play a critical role in determining how the surface current distribution responds to different frequencies, resulting in the observed patterns.