Compact and Closely Spaced Metamaterial MIMO Antenna With High Isolation for Wireless Applications

This letter presents a design of a two-element multiple-input-multiple-output (MIMO) metamaterial-based antenna. The two antenna elements operate at 5.8 GHz for wireless applications. The two antenna elements are designed employing only one left-handed unit cell. The reduction of mutual coupling between the two antenna elements is achieved by using a simple defected ground structure between them to limit the surface waves between them. The distance between the two antenna elements is only 1.8 mm (0.034 λ0). The designed antenna elements have better than -45 dB coupling isolation between the two inputs. Moreover, the proposed MIMO antenna has the advantage of compactness (its size is only 2.36 × 2.6 cm²). The design represents size reduction of more than 50% compared to conventional patch antennas operating at the same frequency. The proposed MIMO system has -55 dB correlation coefficient between its two elements.