Free space mutual coupling reduction between two SIW antennas at millimeter-wave frequency

A low-mutual coupling MIMO antenna system is presented in this paper. A cavity backed SIW antenna is designed to work at the millimeter-wave frequency at first. Then two elements of the designed antenna were integrated to achieve an MIMO system. In order to reduce the free space radiation mutual coupling, an AMC wall was inserted between two antennas. In order to design an AMC wall, a unit cell was simulated with periodic boundary condition. Scattering parameters show that a better isolation of -30 dB is achieved by using the AMC wall. Good isolation, radiation efficiency, and gain make the proposed antenna a good candidate for 5G frequency band.