A Low Mutual Coupling Two-Element MIMO Antenna with a Metamaterial Matrix Loading

A low mutual coupling two-element multiple-input multiple-output (MIMO) antenna with a loading metamaterial structure is proposed numerically and experimentally. The proposed MIMO antenna operating at 5.5 GHz consists of a two-element patch antenna array and a metamaterial structure which is to reduce the coupling between the two patch antenna elements for a small radar applications. In this design, the edge-to-edge distance between two patch elements is set to be 2 mm, which is closely installed and uses the same ground plane. The proposed metamaterial structure blocks the propagation of the electromagnetic waves from the original propagation path along the substrate. The numerical and experimental results demonstrate that the mutual coupling between the antenna elements is reduced to less than -20 dB in the operating band.