## 6 Conclusions  
This paper explores MIMO antennas integrated with SCSRR-based DGS across various feed networks, comparing their performance. Four standard feed methods were carefully evaluated in terms of MIMO antenna performance parameters. The primary goal was to identify and address a research gap: the lack of performance analysis for different feed networks using identical DGS structures, offering valuable insights for future investigators. Initially, it was thought that antennas with DGSs would operate similar to those without DGSs. Nevertheless, a detailed study revealed that the DGS structure significantly impacts the antenna bandwidth and isolation, with proximity- or aperture-coupled feed methods proving more suitable for wideband applications. Furthermore, coaxial probe and microstrip line feed approaches excel in high isolation and straightforward fabrication. Thus, optimizing the DGS shape and dimensions is crucial to match specific feeding technique requirements. Moreover, it is noted that researchers often rely on the time-intensive trial-and-error method to examine ground plane current distribution for  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Parameters** & \multicolumn{2}{c}{**Coaxial Probe**} & \multicolumn{2}{c}{**Microstrip Line**} & \multicolumn{2}{c}{**Proximity Coupled**} & \multicolumn{2}{c}{**Aperture Coupled**} \\ \hline
**Experiment** & **Simulated** & **Measured** & **Simulated** & **Measured** & **Simulated** & **Measured** & **Simulated** & **Measured** \\ \hline \(f_{\mathrm{c}}\) [GHz] & 5.8 & 5.8 & 5.87 & 5.87 & 5.75 & 5.75 & 5.85 & 5.85 \\ \hline BW [MHz] & 180 & 150 & 175 & 125 & 270 & 312 & 225 & 312 \\ \hline Peak gain [dBi] & 6 & \(\approx\)5 & 6.4 & \(\approx\)5 & 6 & \(\approx\)5 & 6.33 & \(\approx\)5 \\ \hline Peak isolation [dB] & 58 & 46 & 24 & 22 & 31 & 38 & 17 & 17 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Impact of different feed networks on the performance of MIMO antennas with SCSRR DGS.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Aim: To Enhance** & **Accomplishment** & **Utilized Feed Type** & **Recommende Feed Type: by Us** \\ \hline
[107] & Isolation & 25 dB & Microstrip line & Coaxial probe \\ \hline
[108] & Isolation & 15 dB & Microstrip line & Coaxial probe \\ \hline
[109] & Isolation & 18.7 dB & Microstrip line & Coaxial probe \\ \hline
[110] & Isolation & 18 dB & Microstrip line & Coaxial probe \\ \hline
[111] & Bandwidth & 260 MHz & Microstrip line & Aperture or proximity coupled \\ \hline \hline \end{tabular}
\end{table}
Table 9: Feed mechanism employed by state-of-the-art DGS-based antennas.  
DGS benefits. Alternatively, evaluating the dispersion diagram of a unit DGS cell offers a quicker approach to determine the EBG range. Future research avenues could involve developing standard equations to predict DGS architectures, benefiting various disciplines. Given DGS's cost-effectiveness in enhancing MIMO antenna performance, its application extends to the design of other radio frequency circuits.  
Conceptualization, M.T.Y., S.K. and P.S.; methodology, M.T.Y., S.K. and P.S.; software, M.T.Y. and S.K.; validation, S.K.; investigation, M.T.Y.; resources, M.T.Y. and S.K.; data curation, M.T.Y. and S.K.; writing--original draft preparation, M.T.Y. and S.K.; writing--review and editing, P.S. and G.P.F.; visualization, M.T.Y. and S.K.; supervision, P.S. and G.P.F. All authors have read and agreed to the published version of the manuscript.  
This work was financed on the basis of the budget passed by the Saxon State Parliament.  
Not applicable.  
The data supporting the reported results in this study are not available due to confidentiality restrictions.  
Authors [PERSON], S.K., [PERSON], and [PERSON] were employed by the company Barkhausen-Institut gGmbH. All authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.