MIMO Antenna System for Multi-Band Millimeter-Wave 5G and Wideband 4G Mobile Communications

A multiple-input multiple-output (MIMO) antenna system is proposed for fifth generation (5G) and fourth generation (4G) mobile communication. The design meets all of the requirements of both 5G and 4G antennas using only a single structure. Since 5G will work at millimeter-wave (mm-Wave), the proposed design serves triple bands at mm-Wave (28, 37 and 39 GHz) for 5G in addition to 2 GHz band (1.8–2.6) for 4G. Each MIMO element consists of a slot-based antenna, fed by two microstrip feeders for the 5G and 4G bands. The design works as a tapered slot antenna at mm-Wave offering end-fire radiation for 5G and works as an open-ended slot antenna for a 2 GHz band offering omni-direction radiation for 4G. The slot antenna type used in the proposed design produces wide bandwidths for the 5G and 4G. The overall volume of each MIMO antenna element is <inline-formula> <tex-math notation="LaTeX">$0.21\times 0.10 \times 0.003\,\,\lambda ^{3}$ </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> is the wavelength of the lowest operating frequency. As a proof of concept, a prototype is developed and tested. The measured results show a wide impedance bandwidth of <inline-formula> <tex-math notation="LaTeX">$|S_{11}| < $ </tex-math></inline-formula> −10 dB covering the band 27.5–40 GHz for 5G, and impedance bandwidth of <inline-formula> <tex-math notation="LaTeX">$|S_{11}| < $ </tex-math></inline-formula> −6 dB covering the band 1.8–2.6 GHz for 4G.