A Low-Profile Wideband Endfire-Broadside Integrated mmWave Phased Array Antenna for 5G Smartphones

Addressing the critical challenge of unpredictable user behavior in mobile terminals on spatial coverage, this letter proposes a low-profile wideband endfire-broadside integrated 5G millimeter-wave (mmWave) antenna array. The antenna element integrates metasurface as the broadside radiator and dipole as the endfire radiator. The proposed antenna array covers -8 dB bandwidth of n258 (24.25-27.50 GHz) and n257 (26.50-29.50 GHz), achieving dual-directional ±50° beam coverage while maintaining the profile of only 0.15λ₀. Furthermore, the long slots are introduced as the decoupling structure, increasing the isolation between endfire and broadside elements from 15 dB to 20 dB. This modification further enhances the active Sparameters of the array, resulting in a maximum gain increase of approximately 2 dB. This design strategy provides a promising solution for future 5G/6G mmWave smartphone antennas due to its low profile, wide bandwidth, and good spatial coverage.