A Compact Four Port Ground-Coupled CPWG-Fed MIMO Antenna for Wireless Applications

In this article, a low profile four element coplanar waveguide ground (CPWG) fed multiple input multiple output (MIMO) antenna having designed footprint of 1.65 × 1.65λ (at 5.5 GHz) is developed for Wi-Fi 5 (5.15–5.85 GHz) and Wi-Fi 6 (5.925–7.125 GHz) access point and repeater applications to satisfy the increasing demands of wireless communication. Each antenna element that is applied for MIMO configuration, consists of a Y-shaped monopole top-loaded by an inverted-C structure (ICS), in which the two open-ends of the ICS are coupled to the two-side ground forming a symmetrical ground-coupled loop antenna structure. Further four identical antenna elements are arranged in a sequential clockwise manner to suppress the mutual coupling among antenna elements forming a 4-port MIMO antenna structure. To enhance the isolation between the adjacent antenna elements, the partial ground planes of all 4 elements are meticulously connected by a whirligig isolating structure. The proposed 4-port MIMO antenna is fabricated and tested for the validation of design, scattering and radiation performances as well as MIMO diversity parameters. Besides yielding a very wide measured 10-dB impedance bandwidth of 35.45% (5.15–7.37 GHz) with isolation better than 25 dB, the designed 4-port MIMO antenna has also demonstrated acceptable gain and radiation efficiency of 4 dBi and 74%, respectively. Furthermore, desirable MIMO performances like envelope correlation coefficient (ECC) less than 0.008, diversity gain (DG) ~ 10 dB and channel capacity of around 21 bps/Hz are also calculated across the bands of interest.