Dual-polarized stacked microstrip antenna with trident-shaped baluns for MIMO array development

摘要

Owing to the high cross-polarization discrimination (XPD) and high isolationcharacteristics, differential excitation is often employed in dual-polarizedmicrostrip antennas. However, the number of excitation ports will be doubled,and the power dividers in the differential circuit will introduce additional loss,the differential excitation scheme is thus not suitable for dual-polarized largescaleMIMO antenna arrays. In this work, a novel dual-polarized stackedmicrostrip antenna with trident-shaped baluns is proposed for base stationMIMO array development. The trident-shaped balun is proposed to replace thetraditional differential excitation structures, while keeping the merits of highXPD and high isolation. The proposed antenna operates in the frequency bandof 3.3-3.8 GHz. The profile height of the antenna is only 0.09λ_0 (λ_0 is the freespacewavelength at the central frequency), which is much lower than traditionalbase station antennas (0.25λ_0) in the sub-6 GHz band. Moreover, adefective ground structure is implemented in a 2×2 MIMO antenna array toefficiently suppress the mutual coupling among antenna elements. Both simulatedand measured results validate the design. Owing to its low-profile heightand low mutual coupling characteristic, the proposed design is a good candidatefor sub-6 GHz band base station MIMO array developments.