Low-Profile MIMO Trapezoidal Patch Antenna for 5G Wideband Mobile Antenna Application

This letter proposes a low-profile trapezoidal patch quad antenna for 5G broadband mobile applications. The multiple-input–multiple-output (MIMO) four-antenna is printed on an FR4 glass fiber substrate with a size of 42 mm × 42 mm (about 0.581λ × 0.581λ at 4.15 GHz) and a thickness of 0.4 mm. The system ground plane is 42 mm × 42 mm, and the air layer is 1.6 mm above the ground plane. The total cross-sectional height is only 2.0 mm (about 0.027λ at 4.15 GHz). The antenna features four identically sized coupled feed structures, each with a 90° rotated trapezoidal patch antenna. A shorting pin near the feeding point is added to improve matching and isolation, successfully covering the sub-6-GHz broadband spectrum from 3.3 GHz to 5.0 GHz and achieving a 41% bandwidth at 4.15 GHz. The isolation between antennas is more than 10 dB. The calculated envelope correlation coefficient values are less than 0.13. The radiation efficiency of the four antennas has been measured to exceed 40%.