8×8 MIMO antenna system with coupled-fed elements for 5G handsets

In this paper, a new design of multiple-input/multiple-output (MIMO) antenna is proposed for 3.6 GHz fifth generation (5G) mobile communications. The proposed design contains four pairs of compact microstrip-fed dual-polarized antennas that are symmetrically placed at the four corners of the smartphone printed circuit board (PCB). Each antenna pair consists of a square loop radiation patch and a square defected ground structure (DGS). The loop radiators are fed by two independently coupled T-shaped microstrip feeding lines, which can exhibit radiation pattern and polarization diversity. Therefore, the proposed 5G smartphone antenna design contains four horizontally polarized and four vertically-polarized antennas in total. A low-cost FR-4 dielectric (ε= 4.4, δ= 0.02) with a dimension of 75×150 mm ² is used as the PCB substrate. The characteristics of the smartphone antenna are examined using both simulations and measurements. It offers good isolation, dual-polarized full radiation coverage, and sufficient efficiency. In addition, the calculated envelope correlation coefficient (ECC) and total active reflection coefficient (TARC) of the design are very low over the entire operation band.