Miniaturized MIMO Antenna Design Based on Mode Cancellation Method for 5G Mobile Terminals

In this letter, a miniature multiple-input-multiple- output (MIMO) antenna pair operating at the 3.5 GHz band is proposed for 5G mobile terminals. The design consists of dual inverted-F antennas (IFAs) arranged in an asymmetric mirrored configuration with respect to the chassis ground plane, occupying a compact size of 12×5 mm^². By adding an inductor at the center of the 1-mm-wide gap between the two closely-spaced IFAs, the mutual coupling is greatly reduced. The decoupling mechanism is explained from the perspective of common mode (CM) and differential mode (DM) cancellation. A prototype of the proposed antenna pair is fabricated. The measured -6 dB overlapping bandwidth of the two ports covers the 3.4-3.6 GHz band, with port isolation higher than 22.4 dB.