Integration of 5G Rectangular MIMO Antenna Array and GSM Antenna for Dual-Band Base Station Applications

In this paper, a dual-band dual-polarized antenna array is presented for 5G base station application. The developed antenna array consists of a 4 × 4 planar MIMO array operating at 3.3-5.0 GHz band (upper band UB) and a single antenna element working at 0.69-0.96 GHz band (lower band LB). The dual-band operation is based on our previously proposed antenna topology. The novelty of this paper is that the UB antenna array is a large-scale rectangular lattice array with 16 antenna elements for practical MIMO applications. Meanwhile, both the cross-band and in-band mutual coupling among the LB and UB antennas are furtherly suppressed by employing three decoupling techniques including rectangular ring resonator, ferrite chock ring, and novel baffle structure. With these decoupling technologies, the UB antenna array and the LB antenna are successfully integrated within a compact volume of 0.93λ L × 0.93λ L × 0.17λ L (λ L is the wavelength at 0.82 GHz). Experimental results show that the proposed dual-band antenna array offers high cross-band port isolation (>30 dB). Stable radiation patterns are also achieved for both the LB and UB antennas with averaged gain of 8.6 dBi and 7.3 dBi, respectively. The radiation efficiency is higher than 90% across the entire operation bands. It is the first time to realize a large scale sub-6 GHz MIMO antenna array shared-aperture working with a GSM band antenna element in a such compact volume.