Metamaterial-based highly isolated MIMO antenna system for 5G smartphone application

A two-port multiple-input-multiple-output (MIMO) antenna system operating in the mm-wave band for 5G applications is presented. The two elements of MIMO structure are separated from each other by 19 mm (1.9 lambda$$ \lambda $$) and excited by microstrip feed. The MIMO elements are circular patches with round cuts at the edges to improve impedance bandwidth. Quadrilateral slot in the ground plane is designed to improve the radiation characteristics of the radiating element having size 18 x19x$$ \times 19\times $$ 0.8 mm(3). The MIMO design is simulated through CST. The proposed antenna works in 27-29 GHz range, providing a potential bandwidth of 2 GHz. Furthermore a gain is improved from 8.2 to 8.75 dB and efficiency increase from 85% to 88% and high isolation of 64 dB is achieved by placing 4-elements of metamaterial with size 4.5 x$$ \times $$ 18 mm(2) in the middle of two circular monopole antennas. The metamaterial gives us a band stop response and act as decoupler and enhance the isolation to reduce mutual coupling. By analyzing the radiation characteristics of the proposed design, in term of reflection coefficient, surface currents, reduced mutual coupling, suitable gain, envelope correlation coefficient (ECC), diversity gain (DG) and radiation pattern, the recommended antenna can be considered a good candidate for 5G applications.