MIMO Antennas for Smart 5G Devices

Abstract

This paper presents the design of $8 \times 8$ multiple-input multiple-output (MIMO) antennas for future 5G devices, such as smart watches and dongles. Each antenna of the MIMO configuration occupies $3 \times 4$ mm2 and is printed on the top layer of the substrate in the form of a rotated H-shaped patch. The substrate used for the design is a $31.2 \times 31.2 \times 1.57$ mm3, Rogers RT-5880 board, with a dielectric constant of 2.2. The top layer of the substrate has eight MIMO antennas, whereas the bottom layer is composed of ground plane. The ground plane is an electromagnetic bandgap-based structure designed for the enhancement of gain and efficiency. Each antenna is fed from the bottom layer of the substrate through vias to avoid any spurious radiation. The MIMO antennas resonate at 25.2 GHz with a 6-dB percentage bandwidth of 15.6%. The gain attained by the antennas in the entire bandwidth is above 7.2 dB with a maximum value of 8.732 dB at the resonant frequency. Likewise, the value of efficiency attained by the antennas in the entire bandwidth is above 65% with a maximum value of 92.7% at the resonant frequency. The simulation and measurement results have substantiated a good performance of the MIMO antennas, thus making them suitable for compact 5G devices.