Isolation Improvement in Closely Coupled MIMO Antenna

In this communication, a double-layer of metasurface based isolation method is proposed to reduce the mutual coupling MIMO (multiple input multiple output) antenna's elements at the 3.5GHz. The double-layer metasurface composes of periodic structure pair of even cut patches with exact same lengths. The main advantage of using a double-layer metasurface layer is there is no additional matching technique is employing in antenna structure to compensate for the matching condition of the antennas. The simualated result shows that mutual coupling among two antennas is enhanced to more than 47dB at 3.5GHz frequency while their reflection coefficients remain to be below -10dB after the double-layer metasurface superstrate is introduced. furthermore, the radiation efficiency is improved to 18% at 3.5GHz and the envelop correlation coefficient (ECC) of MIMO antenna is reduced from 0.08 to 0.0014 at 3.5GHz. MIMO antenna shows excellent performance that makes it a promising contender for the 5G communication system.