A Meta-Surface Decoupling Method for Two Linear Polarized Antenna Array in Sub-6 GHz Base Station Applications

In this paper, an extremely compact two-element linear polarized multiple-input-multiple-output (MIMO) antenna array with a metasurface superstrate is proposed. Instead of using periodic square split-ring resonators which occupy larger space and which are incident angle variant, double-layer short wire is utilized as the unit cell of the metasurface. The metasurface is compact in size and effective in decoupling two nearby Bowtie antennas strongly coupled in the H-plane with the spacing of only 0.27 wavelength. After decoupling, the isolation between the two antennas has been improved from around 10 dB to more than 25 dB within the band of 2300 to 2690 MHz while their reflection remained below −15 dB. Moreover, the radiation pattern after adding the metasurface superstrate is well maintained with total efficiency improvement by about 10%, and the envelope correlation coefficient between the two antennas is reduced from 0.35 to below 0.12 within the whole band of interest. The proposed method can find plenty of applications in MIMO and 5G communication systems.