## 3 Results and Discussion
### Measurement Results
Findings reveal the essentiality of precise simulations together with thorough real-world experiments towards optimizing MIMO antenna characteristics for superior real-world functionality. Figure 12 compares the simulated and measured S-parameters of the four-port MIMO antenna. The results demonstrate a strong correlation between the simulated and experimental data, indicating a significant reduction in mutual coupling among the MIMO ports. This alignment reflects a high degree of isolation across all three frequency bands, emphasizing the efficacy of the metamaterial design in improving MIMO isolation. The enhanced isolation minimizes inter-port interference, thereby optimizing antenna performance and contributing to improved reliability and efficiency in wireless communication systems. Figure 11: Measured and simulated reflection coefficients for each MIMO port, S\({}_{11}\), S\({}_{22}\), S\({}_{33}\), and S\({}_{44}\). Table 2 presents a comparison dataset compiling the latest reports that benchmark the proposed design. Indeed, the proposed design has produced a very competitive result, according to the various antenna metrics of bandwidth gain and isolation. The comparative analysis, however, indicates the superiority offered by using the MIMO antenna over other existing antenna designs in terms of increased bandwidth efficiency, gain, isolation specifications, and overall performance. By considering the proposed design in the light of recent advances, this evaluation demonstrates its effectiveness and great potential in ushering MIMO antenna technology into the next-generation wireless communication system. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Reference No.**} & \multicolumn{2}{c}{**Operating Frequency Frequency (GHz)**} & \multirow{2}{*}{**No. of Ports**} & \multicolumn{2}{c}{**Dimensions Bandwidth (GHz)**} & \multirow{2}{*}{**Gain (dBi)**} & \multirow{2}{*}{**Isolation (dB)**} \\ \cline{1-1}  & & & & & & \\ \hline
[33] & 28 & 4 & 30 \(\times\) 35 & 4.1 & 8.3 & 22 \\ \hline
[34] & 28 & 4 & 32 \(\times\) 8 & 2.6 & 7.5 & 25 \\ \hline
[35] & 28/38 & 2 & 55 \(\times\) 110 & 1.07/1.43 & 7/8 & 27 \\ \hline
[36] & 28/38 & 2 & 7.5 \(\times\) 8.8 & 1.23/1.06 & 6.6/5.86 & 20 \\ \hline
[37] & 28/39/48.7 & 2 & 10 \(\times\) 16 & 1.8/6.2/3.8 & 9.5/11.5 & 17 \\ \hline This work & 28.8 & 4 & 48 \(\times\) 65 & 2.0 & 15 & \textgreater{}40 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparing the achieved results of this design with those of other designs in terms of various evaluation metrics. Figure 12: Simulated and measured S-parameters of 4-port MIMO antenna. Considerable coupling between elements in a MIMO configuration can be very detrimental to system performance because it tends to impend substantial surface wave interactions. Therefore, a deliberate attempt must be made to make it very possible to reduce interference or crosstalk between antenna elements. The results in this work were coupling reductions of \(-40\) dB. This is good evidence to show that the undesirable coupling effects have been reduced, leading to better isolation and improved performance over tri-band operation because such significant mutual coupling reduction proves the effectiveness of the proposed design strategies for making MIMO antenna systems more reliable and efficient for wireless communication.