Tri-Port Antenna With Shared Radiator and Self-Decoupling Characteristic for 5G Smartphone Application

A novel self-decoupling tri-port antenna is proposed. The three ports of the proposed antenna simultaneously excite a radiator printed on the inner surface of the smartphone frame. Based on the mode cancellation method and active reflection coefficient theory, the self-decoupling mechanism of the proposed antenna is investigated. The results reveal that the three ports remain well isolated and no decoupling structure is required. The simulated results illustrate that the isolation of the proposed tri-port antenna is higher than 11 dB in the LTE 42 band, and the envelope correlation coefficients (ECCs) are less than 0.14. A $12\times12$ multiple-input–multiple-output (MIMO) antenna system consisting of four tri-port antennas is designed, manufactured, and measured. The measured results show that the isolation among the 12 ports is better than 10 dB, and the ECCs are less than 0.14. The total efficiency of all ports is 51%–71%. The calculated channel capacity ranges from 57.98 to 59.87 bps/Hz when the signal-to-noise ratio (SNR) is 20 dB.