Design of a tri-band multiple input multiple output antenna with high isolation for 5G applications

A novel tri-band multiple input multiple output (MIMO) antenna with high-isolation is proposed in this article. The proposed tri-band MIMO antenna consists of two tri-band monopole antennas placed symmetrically. Due to the ground surface wave, a defected ground structure (DGS) is etched to extend the ground surface current and reduce the port-to-port coupling. Then two ground branches are loaded on the ground plane as a reflector that inhibit and reflect the coupling between the two parasitic elements. In order to suppress the space surface waves, a novel non-connected neutralization structure is loaded on the microstrip line of two monopole antenna elements. As a result, the quite good isolation and impedance matching are obtained by generating different resonance at different frequency of the structure. Finally, the proposed tri-band MIMO antenna with the decoupling structure achieves 5G tri-band of 2.5–2.7, 3.26–3.83, and 4.73–4.97 GHz (S11&S22 < −10 dB, S12 & S21 < −25 dB). The results show that the proposed tri-band MIMO antenna can cover the whole 5G bands (sub-6 GHz) and has good isolation characteristic, which can well meet the 5G applications.