## 6 Conclusions  
This study presents a two-port, dual band-notch UWB antenna based on neutralization line (NL). The NL serves as a decoupling device in the connection between the two similarly situated dual band-notch UWB antennas. The NL improves the MIMO system's isolation between the antenna elements by producing the opposing current to the coupling current.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & \multirow{2}{*}{**Techniques Used**} & \multirow{2}{*}{**Techniques Used**} & \multirow{2}{*}{**Dimensions (bg3, at a Center**} & \multirow{2}{*}{**Impedance Bandwidth**} & \multirow{2}{*}{**Isolation (dB)**} & \multirow{2}{*}{**ECC**} & \multirow{2}{*}{**DG**} & \multirow{2}{*}{**MEG**} & \multirow{2}{*}{**TARC**} & \multirow{2}{*}{**CCL**} & \multirow{2}{*}{**ME**} \\  & & & **Frequency** & & & & & & & & \\ \hline
[17] & DQS & \(1.2\times 0.9\times 0.05\) & 2-10.6 & \(>\)22 & \(<\)0.1 & - & - & - & - & - \\
[30] & Stub and DCS & \(2.5\times 1.1\times 0.01\) & 2.5\(\times\)12.2 & \(>\)15 & \(<\)0.005 & \(\approx\)10 & - & - & \(<\)0.4 & - \\
[31] & DCS & \(1.0\times 1.2\times 0.06\) & 3.18–11.26 & \(>\)22 & \(<\)0.06 & \(<\)9.7 & - & - & \(<\)0.4 & - \\
[32] & DCS with EBG & \(1.0\times 1.2\times 0.03\) & 3.1–11 & \(>\)25 & \(<\)0.01 & \(>\)9.99 & - & - & \(<\)0.1 & - \\
[33] & Neutralization line & \(0.7\times 0.7\times 0.01\) & 3-15 & \(>\)22 & \(<\)0.1 & - & - & - & - & - \\
[34] & DQS and parasitic element & \(1.5\times 1.2\times 0.03\) & 3–11 & \(>\)20 & \(<\)0.02 & \(\approx\)10 & - & - & - & - \\
[35] & parasitic element and EBG & \(1.6\times 1.3\times 0.06\) & 3–10.7 & \(>\)25 & \(<\)0.001 & \(\approx\)10 & - & - & - & - \\ proposed & Neutralization line & \(0.9\times 1.2\times 0.06\) & 3.4–12.1 & \(>\)16 & \(<\)0.001 & \(\approx\)10 & \(\sim\)–3 & \(<\)–10 & \(<\)0.3 & \(<\)–2 \\ \hline \hline \end{tabular} - Not available.  
\end{table}
Table 7: Performance comparison of the projected antenna with the designs available in the literature.  
Figure 22: MIMO diversity metrics of the projected antenna (**a**) ECC and DG, (**b**) MEG and TARC, (**c**) CCL and ME.  
The proposed design has a simple and effective structure with compact dimensions of 0.24 \(\times\) 0.31 \(\times\) 0.01 \(\lambda^{3}\), operating in the frequency range of 3.4 to 12.1 GHz, except for the frequency band notching of 4.5-5.3 GHz and 7.2-9 GHz. The port-to-port isolation is greater than 16 dB across the impedance bandwidth. The time-domain characteristics GD is less than 1 ns except for the notched frequency bands, and FF is greater than 0.96 in side-to-side and face-to-face orientation. The MIMO diversity parameters have ECC\(<\) 0.3, DG \(>\) 9.6 dB, MEG \(<-\)3 dB, TARC \(<-\)10 dB, CCL \(<\) 0.3 bps/Hz, and ME \(<-\)2 dB across the operational frequency, all other than the serrated bands, and characteristic mode analysis are also considered for the antenna design. The projected antenna is suitable for MIMO wireless communication, according to the numerical and experimental results. Future studies will concentrate on expanding the number of sending and receiving antennas to increase the channel capacity. The proposed decoupling approach can also be integrated with other ways as a hybrid decoupling structure to improve isolation among the antenna elements.  
Conceptualization: P.K., M.P.M. and T.A.; methodology: P.K., M.P.M. and T.A.; software P.K., M.P.M. and T.A.; data citation: P.K., M.P.M. and T.A.; writing--P.K. and T.A.; supervision: T.A. and M.P.M. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The authors declare no conflict of interest.