Embedded two dimensional metamaterial structure in MIMO antenna array for mutual coupling reduction

In this paper, a practical scheme is studied to reduce mutual coupling interference (MCI) between two extremely adjacent MIMO (multiple input multiple output) antenna elements, where the two-dimensional metamaterial units with 1 × 7 meta-FCRR1 (fold complementary ring resonator) and 5 × 7 double-layer meta-FCRR2 are etched to suppress the surface wave. The proposed metamaterial can well match the left hand electromagnetic in electromagnetic field, and the meta-FCRR1 + 2 as a miniature notch filter is equivalent to a negative permeability medium. Then, the microstrip antenna array using the co-planar waveguide mode is fabricated and the measured results are compared with the simulation. The results indicate that the MCI of antenna array with meta-FCRR1 + 2 are effectively reduced to 26 dB and 24 dB at resonance frequency of interest (2.45 GHz and 4.6 GHz). And the approximately 16.67% and 13.3% matching impedance bandwidth are obtained at the return loss S11 < − 10 dB. And the total efficiency, the envelope correlation coefficient (ECC), diversity gain (DG), voltage standing wave ratio (VSWR) are presented to verify the better performance of MIMO antenna array by suppress the MCI.