## 3 Results and Discussion
### Far-Field Results  
For the verification of the far-field characteristics of the proposed integrated antenna, the fabricated antenna was tested in a shielded RF anechoic chamber. The testing setup images for the mid-band and high-band antennas are shown in Figure 13. The simulated and the measured GAIN results for the integrated antenna design are reported in Table 2. It can be noted that the measured and simulated gain have low residual error. Figure 11: S-parameter measurement hardware setup. The 2D radiation patterns of the integrated design are measured in the same chamber as mentioned for the GAIN. The radiation pattern corresponding to theta = 90 and phi = 90 plane for the simulated and measured radiation pattern at 3.8 GHz are reported in Figure 14. Similarly, the simulated and measured radiation patterns at 27.5 GHz are reported in Figure 15. Here, it can be noted that, at both frequencies, the simulated and measured radiation patterns have a good correlation with each other; however, at the lower frequency of 3.8 GHz, slight differences were observed, which are due to manufacturing impairments, while, at the higher frequency of 27.5 GHz, some ripples showed up because of unavoidable mismatches that happen at the higher frequency. Figure 12: Scattering parameters for the mid-band (4G LTE and lower 5G) and high-band (5G mmWave) MIMO antennas integrated design: (**a**) measured and simulated scattering parameters for the mid-band (4G LTE and lower 5G) MIMO configuration; (**b**) measured and simulated reflection parameters for the high-band (5G mmWave) MIMO configuration; (**c**) simulated transmission parameters for the high-band (5G mmWave) MIMO configuration; (**d**) measured transmission parameters for the high-band (5G mmWave) MIMO configuration. _Appl. Sci._**2021**, _11_, 8331 \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sr. No**} & \multirow{2}{*}{**Frequency (GHz)**} & \multirow{2}{*}{**Antennas**} & \multicolumn{2}{c}{**GAIN (dBi)**} \\ \cline{3-5}  & & & **Simulated** & **Measured** \\ \hline \multirow{2}{*}{1} & \multirow{2}{*}{3.3} & Antenna-1 & 2.95 & 2.87 \\ \cline{3-5}  & & Antenna-2 & 2.95 & 2.75 \\ \hline \multirow{2}{*}{2} & \multirow{2}{*}{3.8} & Antenna-1 & 3.06 & 2.86 \\ \cline{3-5}  & & Antenna-2 & 3.06 & 2.85 \\ \hline \multirow{2}{*}{3} & \multirow{2}{*}{4.8} & Antenna-1 & 4.23 & 3.93 \\ \cline{3-5}  & & Antenna-2 & 4.23 & 3.83 \\ \hline \multirow{2}{*}{4} & \multirow{2}{*}{5.2} & Antenna-1 & 5.29 & 4.96 \\ \cline{3-5}  & & Antenna-2 & 5.29 & 4.84 \\ \hline \multirow{2}{*}{5} & \multirow{2}{*}{24.5} & Antenna-3 & 5.18 & 5.09 \\ \cline{3-5}  & & Antenna-4 & 5.18 & 5.06 \\ \cline{3-5}  & & Antenna-5 & 5.93 & 5.81 \\ \cline{3-5}  & & Antenna-6 & 5.93 & 5.77 \\ \hline \multirow{2}{*}{6} & \multirow{2}{*}{25.5} & Antenna-3 & 6.89 & 6.66 \\ \cline{3-5}  & & Antenna-4 & 6.89 & 6.55 \\ \cline{3-5}  & & Antenna-5 & 6.99 & 7.66 \\ \cline{3-5}  & & Antenna-6 & 6.99 & 7.56 \\ \hline \multirow{2}{*}{7} & \multirow{2}{*}{26.5} & Antenna-3 & 7.49 & 7.22 \\ \cline{3-5}  & & Antenna-4 & 7.49 & 7.13 \\ \cline{3-5}  & & Antenna-5 & 7.49 & 7.24 \\ \cline{3-5}  & & Antenna-6 & 7.49 & 7.23 \\ \hline \multirow{2}{*}{8} & \multirow{2}{*}{27.5} & Antenna-3 & 7.69 & 7.54 \\ \cline{3-5}  & & Antenna-4 & 7.69 & 7.44 \\ \cline{3-5}  & & Antenna-5 & 7.78 & 7.43 \\ \cline{3-5}  & & Antenna-6 & 7.78 & 7.55 \\ \hline \multirow{2}{*}{9} & \multirow{2}{*}{28} & Antenna-3 & 8.52 & 8.38 \\ \cline{3-5}  & & Antenna-4 & 8.52 & 8.40 \\ \cline{3-5}  & & Antenna-5 & 8.57 & 8.42 \\ \hline \end{tabular}
\end{table} 
Table 2: Simulated and measured gains for the mid- and high-band MIMO antennas. Figure 13: Antenna far field-testing setup: (**a**) mounted high-band (5G mmWave) antenna; (**b**) mounted mid-band MIMO, front; (**c**) mounted mid-band MIMO, back. The measured and simulated radiation patterns are different due to the non-ideal manufacturing process and the limitation of the testing and measuring equipment.