A New Broadband MIMO Antenna System for Sub 6 GHz 5G Cellular Communications

Abstract

A new MIMO antenna system with broadband antenna radiators is introduced for sub 6 GHz fifth-generation (5G) mobile communications. The proposed design contains four pairs of compact coplanar-waveguide (CPW)-fed antennas with polarization diversity that are symmetrically placed at four corners of the smartphone printed circuit board (PCB). Therefore, the proposed 5G antenna design contains four horizontally polarized and four vertically-polarized antenna elements in total. A low-cost FR-4 substrate ($\varepsilon_{r} = 4.4$, $\delta = 0.02$) with a dimension of $75 \times150$ mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is employed as the mainboard substrate. The proposed design offers good isolation, dual-polarized full radiation coverage, and sufficient efficiencies. In addition, a wide impedance bandwidth ($S_{11} \le -10 dB$) of 3.3 to 6 GHz has been obtained for each antenna radiator. Moreover, the proposed design exhibits sufficient performance in the presence of the human-hand.