Compact MIMO Monopolar Patch Antenna for 4G and Full Band of 5G Wireless Applications

A multiple-input-multiple-output (MIMO) antenna system for fourth generation (4G) and full band of fifth generation (5G) wireless applications is presented in this paper. The MIMO system consists four identical monopolar patch antennas (MPAs), each MPA acts as a single 4G/5G antenna element and adopted a folded structure for size reduction. Defective ground structure and a kind of folded plane inverted F-shaped (PIF) grounding branch are designed to reduce the surface wave coupling and the near field coupling, port isolation better than -14 dB is achieved within the whole operating bandwidth. The measured results show that the antenna exhibits a quasi-omnidirectional radiation characteristic and the impedance bandwidth (VSWR<3) covering the band 1.57-9GHz. Moreover, the envelope correlation coefficient (ECC) of each-two antenna elements is less than 0.018, which means that the proposed antenna system has good diversity performance.