Low-Mutual-Coupling 60-GHz MIMO Antenna System With Frequency Selective Surface Wall

A new dielectric resonator antenna (DRA) for a millimeter-wave (mm-wave) multiple-input multiple-output system is presented. Two approaches are exploited to reduce the mutual coupling between two antenna elements. First, a frequency selective surface (FSS) wall is inserted between the DRAs to reduce the free-space radiation. Then, two slots with different size acting like an LC resonator are etched from the common ground plane of the structure to reduce the surface current. The designed FSS has a wideband characteristic from 40 to 70 CHz. The FSS is optimized for the desired frequency of 57-63 CHz. A high isolation of 30 dB is achieved when both FSS wall and slots are used. A prototype of the structure is fabricated and measured. The results give a low correlation coefficient (<5e-6) and a good agreement with simulation ones, indicating that the proposed antenna can provide spatial or pattern diversity to increase the data capacity of wireless communication systems at mm-wave bands.