Design of a Polarization Diversity MIMO Antenna With Improved Mutual Coupling

Abstract

In this paper, a 4-element multiple-input-multiple-output (MIMO) antenna at sub-6 GHz spectrum with polarization diversity capability is presented for 5G wireless communication. The proposed MIMO antenna includes four square shaped microstrip patch antennas with two orthogonal ports in each on a finite common ground plane. Two orthogonal input ports help to realize orthogonal linear polarization (horizontal and vertical) and circular polarization (LHCP and RHCP) depending on the input conditions. Therefore, polarization diversity can be achieved for the proposed antenna. Common ground plane is used for some superior advantages, like unwanted electric field suppression, noise reduction etc. For reducing mutual coupling among the MIMO elements, the DGS (Defected Ground Structure) method is utilized in the common ground plane, as DGS have some superior advantages comparing other isolation enhancement technique. As a result, isolation of the proposed antenna is enhanced by −10 dB compared to without DGS (full ground) structure. Moreover, an operating band of 3.45–3.49 GHz with a gain of 8.2 dBi and 8 dBic for LP and CP, respectively is achieved. Furthermore, the envelope correlation coefficient of the proposed MIMO antenna is less than 0.005, that makes it suitable for massive MIMO and 5G wireless applications.