The present work describes a unique planar wideband circularly polarized MIMO antenna for 4G and sub-6 5G band (1.35-2.6 GHz), with pattern diversity over the entire axial-ratio bandwidth. The design consists of two tri-branch planar inverted-F antenna (PIFA) antennas with a ground T-stub between the antennas, which is used to realize circular polarization and high isolation. The third antenna is an integrated sub-6 5G (4.45-4.7 GHz) and LTE band (786.7-807.7 MHz) antenna, which is folded above the ground and placed vertically around the side. It also provides circular polarization at LTE band. The 3 dB axial ratio bandwidth (ARBW) of the MIMO antenna is 1.05 GHz (1.47-2.52 GHz); impedance matching bandwidth (IMBW) is 1.25 GHz (1.35-2.6 GHz); and its isolation is better than 13.4 dB in the whole band. It has fabricated on an FR-4 substrate and is suitable for mobile handset.
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