A Low Profile and Low Cross-Polarization Metasurface Antenna for 5G mm-wave Applications

In this paper, a low profile and low cross-polarization miniaturized metasurface antenna is presented for 5G mm-wave applications. The metasurface consists two different sets of patches in a 3 × 3 configuration; the patches in the middle of the structure have been intelligently loaded with slits and stubs to separate degenerate modes and suppress higher-order modes that appear in a conventional symmetric metasurface. As a result, a miniaturized metasurface antenna with low cross-polarization (XP) level and improved efficiency is achieved. The simulation results of the antenna show the proposed metasurface antenna covers a bandwidth of 19% (24.5 GHz-29.5 GHz) with better than 10 dB return loss, 9 dB peak gain and XP level < -45 dB all over the desired frequency range. The size of the proposed antenna is 0.72λ0 × 0.72λ0 × 0.07λ0 which is 62% smaller than the conventional metasurface antenna. To further investigate the performance of the proposed antenna, it is used in a 2×2 Multiple Input-Multiple Output (MIMO) configuration without any additional inter-element spacing. Since in the new antenna, the higher-order modes are moved to out-of-band frequencies, the beam split and beam squint are not observed in its radiation patterns, which are issues in conventional metasurface antennas.