A 2×2 MIMO Antenna for 28 GHz 5G Communication Applications with High Isolation

Global communications are predicted to radically change with the arrival of fifth-generation (5G) mobile communications technology. This paper proposes a $2 \times 2$ MIMO antenna for 28 GHz broadband communications applications. The design is initiated by designing an antenna for 28 GHz, then a rectangular slot is added to enhance the impedance matching, and finally, a circular patch is inserted. The single element of the anticipated MIMO antenna on the RT5880 substrate resonates at 28.09 GHz with an S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> of $-\mathbf{- 3 9. 3 5 \mathrm { dB } \text {. The MIMO structure has }}$ a volumetric dimension of $30.32 \times \mathbf{3 0. 3 2} \times 1.575 \mathrm{~mm}^{3}$, resonates at 28.13 GHz, and achieves a working bandwidth of 3.07 GHz (26.63 to 29.70 GHz). Moreover, it achieves a maximum isolation of −58.04 dB, a maximum efficiency of $\mathbf{9 9 \%}$, and a peak gain of 7.41 dBi. The achieved ECC $\leq 0.0005$, and the DG is nearer 10 dB. Compared to the recently reported mmWave MIMO antennas, the designed MIMO antenna demonstrates superior performance in terms of operating bandwidth, isolation, gain, efficiency, ECC, and DG, which makes it an effective nominee for 5 GmmWave, satellite, and mobile communication applications.