A Four-Port MIMO Antenna System for 5G Mobile Terminals

A compact 4-port multiple input multiple output (MIMO) antenna system is proposed and developed. It is designed to be operated at Band N77 (3300 - 4200 MHz) for 5G mobile terminals. The proposed MIMO system consists of four antenna elements. Each element includes a monopole on the upper surface and a grounding parasitic stub on the lower surface. Both the monopole and the grounding parasitic stub work together to realize an extended bandwidth to fully cover the 5G NR N77 band. The low-cost FR-4 substrate is utilized with a 3D dimension of 70 mm X 70 mm X 0.8 mm, while the size of the clearance or keepout zone of each antenna element is 16 mm X 7 mm. As the antenna elements are placed orthogonally to each other, the isolation between each port is better than 15 dB without adding any other decoupling structures. A MIMO antenna prototype is fabricated and measured, and a good agreement between simulation and measurement is achieved.