# Multiport Single Element Mimo Antenna Systems: A Review
## 5 Summary
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**References** & **Frequency** & **Size** & **Isolation** & **Isolation** & **ECC** & **Gain** & **Number of **Ports/Application** \\  & **(GHz)** & **(mm2)** & **Technique** & **(dB)** & **(dB)** & **(dB)** & **Number of **Ports/Application** \\ \hline
[76] & 3–11 & \(48\times 48\) & T shaped slot & \(-17\) & \(0.02\) & \(2\)-\(5\) & \(4\)/Ultra-Wide Band \\ \hline
[77] & 3–10.6 & \(36\times 36\) & Stub at ground plane & \(-15\) & \(0.02\) & \(1.5\)-\(4\) & \(4\)/Ultra-Wide Band \\ \hline
[78] & 4.96-5.5 & \(75\times 75\) & Defected patch and ground & \(-12\) & \(0.03\) & \(2.4\)-\(5.5\) & \(4\)/WLAN (S.2) \\ \hline
[79] & 4.4-6.4 & \(75\times 75\) & Defected patch and ground & \(-13\) & \(0.04\) & \(3\)-\(6.1\) & \(4\)/Sub \(6\) GHz applications \\ \hline
[80] & 1.8-2.9 & \(120\times 140\) & Slots at ground, DCS & \(-15\) & \(0.07\) & \(6\) & \(4\)/LTE (Wireless Access Point), WiFi (2.4) \\ \hline
[81] & 2.34-2.56 & \(72\times 72\) & Diagonal parasitic element & \(-12\) & \(0.01\) & \(2\) & \(4\)/WiFi (2.4) \\ \hline
[82] & 35.5 & \(45\times 45\) & Slot technique & \(-35\) & \(0.02\) & \(2\)-\(5\) & \(4\)/WiMAX (S.5,5) \\ \hline
[83] & 2-3 & \(108\times 108\) & Slot technique & \(-12\) & \(0.02\) & \(5.9\)-\(6.2\) & \(4\)/LTE (2.1/2.3/2.6 GHz), Wi-Fi (2.4) \\ \hline
[84] & 4.5-7 & \(95\times 95\) & Ground stub & \(-20\) & \(0.01\) & \(5\) & \(4\)/WLAN (S.2,5.8), WiMAX (S.5) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Shared radiator antenna with four ports. But these antenna configurations suffer minor variations in radiation characteristics behavior due to the asymmetrical nature of the antenna. Therefore, these antennas would be implemented for those applications where the radiation pattern does not substantially affect the performance of the antenna. Besides this, most of the single common element antennas reviewed here are suitable for UWB-MIMO applications. The shared radiator in a MIMO system is an effective method to retain the compactness of the antenna design for the portable devices as compared to separate antenna elements. This also provides unique radiation pattern characteristics, but to design with good isolation is difficult. Hence this paper presents several antennas designs and mutual coupling reduction techniques which would be helpful in designing antenna for future communication systems and in achieving the required performance parameters of the MIMO antennas. In all the above cases, most of the single element antennas reported in the literature are for UWB-MIMO and Wi-Fi/WLAN applications. Hence, it is important in the future, to consider efficient technique to design MIMO antenna with shared radiator for 5G and portable devices. Conceptualization, N.S. and H.T.C. ; methodology, N.S. and T.K.G. ; software, N.S. ; validation, H.T.C. and S.K.A.R. ; formal analysis, H.T.C., N.S. and S.K.A.R. ; investigation, N.S. and S.K.A.R. ; resources, S.K.A.R. and T.K.G. ; data curation, N.S. and H.T.C. ; writing--original draft preparation, N.S. ; writing--review and editing, H.T.C., S.K.A.R. and T.K.G. ; visualization, T.K.G. ; supervision, H.T.C. and S.K.A.R. ; project administration, S.K.A.R. and T.K.G. ; funding acquisition, S.K.A.R. and T.K.G. All authors have read and agreed to the published version of the manuscript. This work was supported in part by the Telekom Malaysia Berhad under the Grant No. MMUE/220012 and FRGS grant FRGS/1/2018/TK08/MMU/02/1 or MMUE/180033. Not applicable. Not applicable. * _[PERSON] et al. (2014)_ [PERSON]; [PERSON] Compact ultrawideband (UWB) slot antenna with wideband and high isolation for MIMO applications. _Prog. Electromagn. Res. C_**2014**, _54_, 9-16. [CrossRef]
* _[PERSON] et al. (2010)_ [PERSON]; [PERSON]; [PERSON]; [PERSON] High isolation compact four-port MIMO antenna systems with built-in filters as isolation structure. In Proceedings of the Fourth European Conference on Antennas and Propagation, Barcelona, Spain, 12-16 April 2010.