Mutual Coupling Reduction of a MIMO Antenna Array Using 3-D Novel Meta-material Structures

A 3-D metamaterial structure (3DMMS) is proposed and is used to reduce mutual coupling of a twoelement patch antenna array. The 3DMMS consists of an upper M-shaped patch and two lower U-shaped patches, which are connected by two shorted pins. The proposed 3DMMS has a negative permeability at 2.35-2.45 GHz band, which covers the operation band of the patch antenna array with an edge-to-edge array-element distance of 0.13 lambda 0. Five designed 3DMMS cells are embedded into the substrate between two antenna elements, which has a 0.1mm vertical distance to the patch antennas. The proposed antenna is optimized, fabricated and measured. The results show that about 18 dB mutual coupling reduction is achieved by using the 3DMMS without affecting the operating bandwidth and radiation characteristics.