# Meta Surface-Based Multiband MIMO Antenna for UAV Communications at mm-Wave and Sub-THz Bands
## 1 Introduction
### The State of the Art and Originality of Study
\begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Ref** & **Antenna Type** & \(f\), **(GHz)** & **Dims. (mm \(\times\) mm \(\times\) mm)** & \
\begin{tabular}{c} **Peak Gain** \\ **(dBi)** \\ \end{tabular} & **MIMO** & **Planar/Nonplanar** & **Single/Multiband** &
\begin{tabular}{c} **UAV Comm.** \\ **Type** \\ \end{tabular} \\ \hline \hline \multicolumn{8}{c}{Antennas designed for UAV communications at different frequency bands} \\ \hline
[11] & Conical beam & 28.3 & 48 \(\times\) 48 \(\times\) 5 & 8.51 & no & Planar & Single band &
\begin{tabular}{c} mm-wave \\ drone \\ \end{tabular} \\ \hline
[12] & Reconfigurable & 5.7 & 84 \(\times\) 84 \(\times\) 13 & 10.2 & yes & Nonplanar & Single band & D2G \\ \hline
[13] & Dipole & 1.25 & 110 \(\times\) 13 \(\times\) 1 & 1.76 & no & Planar & Single band & D2G \\ \hline
[14] & Dipole & 2.4, 4.4 & 58 \(\times\) 58 \(\times\) 0.76 & 8.7 & yes & Planar & Dual band & D2G \\ \hline
[15] &
\begin{tabular}{c} Dual-mode \\ circular patch antenna \\ \end{tabular} & 2.4, 5.2 & 76 & 9.55 & no & Planar & Dual band & D2G \\ \hline
[16] & Horn antenna & 5.4 & \(>\)300 & 16.5 & no & Nonplanar & Single band & D2G \\ \hline
[17] &
\begin{tabular}{c} Dual-mode \\ composite microstrip line \\ \end{tabular} & 5.8–8.5, 35–41.5 & \(>\)250 & 20.6 & yes & Planar & Dual band & mm-wave \\ \hline
[18] & \
\begin{tabular}{c} Patch, magnetic- \\ electric dipole \\ \end{tabular} &
\begin{tabular}{c} 2.40–2.8, \\ 5.15–8.55, 57–64 \\ \end{tabular} & 140 \(\times\) 140 & 9.8 & yes & Planar & Triple band & mm-wave \\ \hline \hline \multicolumn{8}{c}{Antennas utilizing MTS to enhance their performances.} \\ \hline Ref & MTS shape & \(f\), (GHz) & Dims. (mm \(\times\) mm \(\times\) mm) & Peak gain (dBi) & BW (GHz) & Planar/nonplanar & Single-/multiband & Applications \\ \hline
[25] & Cut circular rings & 5.8 & 34.7 & 11.4 & 4–8.5 & Planar & Dual band &
\begin{tabular}{c} LTE, Sub-6 \\ GHz \\ \end{tabular} \\ \hline
[26] &
\begin{tabular}{c} Slotted \\ cutting-edge \\ rectangular \\ \end{tabular} & 5.5 & 80 \(\times\) 80 \(\times\) 1.5 & 5.66 & 5.25-6.35 & Planar & Single band & Sub-6 GHz \\ \hline
[27] & Rectangular & 27 & 65 \(\times\) 55 \(\times\) 1.3 & 11.1 & \
\begin{tabular}{c} 23.89– \\ 31.23 \\ \end{tabular} & Planar & Single band &
\begin{tabular}{c} mm-wave, \\ higher 5G \\ \end{tabular} \\ \hline
[28] & \
\begin{tabular}{c} Slotted \\ mushroom \\ \end{tabular} & 28 & 37.7 \(\times\) 37.7 \(\times\) 1.7 & 19.2 & 24.4-30.5 & Planar & Single band &
\begin{tabular}{c} mm-wave \\ higher 5G \\ \end{tabular} \\ \hline
[29] & Rectangular ring & 27 & 19.7 \(\times\) 19.7 \(\times\) 0.5 & 9.4 & 23.9–30.7 & Planar & Single band &
\begin{tabular}{c} mm-wave, \\ higher 5G \\ \end{tabular} \\ \hline
[30] & \begin{tabular}{c} Split-ring \\ resonator \\ \end{tabular} & 28 & 20.6 \(\times\) 20.5 \(\times\) 0.5 & 12.7 & \
\begin{tabular}{c} 27.38– \\ 33.34 \\ \end{tabular} & Planar & Single band &
\begin{tabular}{c} mm-wave, \\ higher 5G \\ \end{tabular} \\ \hline
[32] & Rectangular & 34 & 12.5 \(\times\) 12.5 & 11.3 & 30–38.58 & Planar & Single band & mm-wave \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Performance comparison of recent related state-of-the-art works for UAV communications at lower and higher bands. To address the challenges and limitations of UAV communications and the applied antennas for these communications, a particular type of antenna should be designed to face all those challenges and obtain promising performances; these should exceed those of the currently available, similarly designed antennas for UAV communications and applied MTS structures, such as those presented in Table 1.  
Contributions: This paper introduces a novel two-port leaky wave MIMO antenna designed to encompass a wide frequency range, catering to various UAV-assisted communication bands.