Dual-polarized broadband base station antenna backed with dielectric cavity for 5G communications

A compact dual-polarized antenna with total dimensions of 31 × 31 × 14 mm³ is proposed for the fifth-generation base stations at 3.5 GHz. The antenna consists of two orthogonal bow-tie dipoles. The bandwidth is enhanced using eight parasitic strips along with the dipole patches, two U-shaped slots around the feeding positions, and dielectric cavity, which brings two resonant frequencies closer to each other. The isolation between the dual polarization is improved by adding two shorting pins symmetrically with respect to the feeding cable. The proposed antenna operates in the range of 3.2-3.9 GHz with S₁₁ ≤-15 dB and has port isolation better than 40 dB. The measured results show good performances in front-to-back ratio, cross-polarization discrimination ratio, and stable radiation patterns. Finally, the proposed antenna is used to construct a 2 × 4 multiple-input-multiple-output (MIMO) antenna with a compact size of 101 × 170 × 14 mm³ (1.16 λ₀ × 1.96 λ₀ × 0.16 λ₀). The MIMO antenna is fabricated and tested. Good results are observed.