Dual-Polarized Dual-Dipole Antenna with Low Mutual Coupling for Massive MIMO

A dual-polarized dual-dipole antenna with low mutual coupling for massive MIMO base stations is proposed. The antenna is composed of two pairs of fold dipole connected by shaped coplanar microstrip lines. The antenna has a bandwidth of 11.5% for return loss>15 dB, covering one of the 5G band (3.3-3.6 GHz). The low mutual coupling of the proposed antenna is validated by simulating a 2 by 2 antenna array. It is shown that the isolation between the input ports with same polarization is higher than 30 dB with an element distance of $0.65\lambda$ (where $\lambda$ is the free-space wavelength at 3.45 GHz) while isolation between the input ports for orthogonal polarization is about 23 dB. Due to the low mutual coupling between the adjacent elements, there is little deterioration for the radiation patterns of the antenna element in the array.