A Four-element MIMO Antenna Array for 5G Smartwatches

This paper presents a simple structure four-element multiple-input multiple-output (MIMO) antenna array for 5G smartwatch applications. Each antenna is a simple F-shaped microstrip line structure. The neutralization line is loaded between two antennas to improve the isolation. The operating bandwidth of the single antenna covers the 5G new radio (NR) bands n77 and n78 with 6-dB impedance bandwidth. The isolation is higher than 10 dB. Furthermore, the proposed MIMO smartwatch antenna array is fabricated and measured.