A　2×2　broadband　multiple-input-multiple-output　(MIMO)　antenna　array　with　high　isolation　for　5G　sub-6-GHz　frequencies　is　presented.　The　MIMO　array　is　composed　of　four　elements　fed　by　a　microstrip.　A　gain　of　3.95　dB　with　a　working　frequency　of　1.15　GHz　(from　3.15　to　4.30　GHz)　is　obtained　in　the　array　element.　Several　slots　were　set　on　the　ground　plane　of　the　array　to　improve　the　isolation　between　different　elements　from　10　dB　to　more　than　20　dB.　The　MIMO　antenna　array　achieved　a　gain　of　8.91　dB　with　the　isolation　between　different　elements　being　more　than　20　dB　in　the　working　frequency.　The　proposed　array　has　the　merits　of　small　size,　wide　bandwidth,　high　isolation,　and　good　symmetry　of　radiation　pattern,　which　are　required　for　5G　sub-6-GHz　applications.　©　2023　IEEE.