A Novel Cross-Band Decoupled Shared-Aperture Base Station Antenna Array Unit for 5G Mobile Communications

In this paper, a novel compact, dual-polarized, dual-broadband shared-aperture antenna array unit consisting of one lower-band (LB) element and four upper-band (UB) elements underneath is proposed for 5G mobile communications. L-shaped parasitic branches are introduced in the LB to broaden the bandwidth while reducing the mutual coupling between the LB element and UB elements. Compared with the traditional lower-band dipole, the proposed LB element has far less influence on the electric field of the UB array, thus preserving their radiation patterns. To verify its performance, the antenna array unit is fabricated and experimentally demonstrated to achieve the bandwidth of 32.7% (0.69–0.96 GHz) in the LB and 45.5% (1.7–2.7 GHz) in the UB with a voltage standing wave ratio (VSWR) of lower than 1.5. High port isolation and stable radiation patterns are attained in both the LB and UB as required for dual-band base station antennas.