A Low-Profile Triple-Band Shared-Aperture Antenna Array for 5G Base Station Applications

In this article, a triple-band shared-aperture dual-polarized antenna array is proposed for fifth generation (5G) base station applications. The shared-aperture antenna array consists of an antenna operating in the low-band (LB) 0.69–0.96 GHz, a $2\times $ 2 antenna array operating in the middle-band (MB) 1.8–2.7 GHz, and a $4\times $ 4 antenna array operating in the high-band (HB) 3.3–3.8 GHz. A wideband bandstop frequency selective surface (FSS) is introduced to eliminate the influence of the LB antenna on the MB/HB antenna array. The MB antenna is co-designed with the wideband bandpass FSS, such that it does not affect the radiation performance of the HB antenna array. Therefore, the LB antenna, MB antenna array, and HB antenna array are successfully integrated within a compact volume of $0.69\lambda _{L} \times 0.69\lambda _{L} \times 0.177\lambda _{L}$ ( $\lambda _{L}$ is the free-space wavelength at 0.69 GHz). Measured results demonstrate that the proposed low-profile shared-aperture antenna array offers stable radiation patterns and an average gain of 6.5, 7.6, and 8.2 dBi in the LB, MB, and HB, respectively. Owing to the wide bandwidth, low-profile height, shared-aperture, and compact size, the proposed antenna array is promising for 5G massive MIMO applications.