Quad-Band MIMO Antenna System for 5G Mobile Handsets

Abstract

An efficient Multi-Input Multi-Output (MIMO) antenna system with a spatial diversity configuration for the Fifth Generation (5G) mobile handsets is constructed from a compact-size quad-band (28/45/51/56 GHz) microstrip patch antennas. The antenna is constructed as primary and secondary patches which are capacitively coupled and designed to realize impedance matching and to produce appropriate radiation patterns in the four frequency bands. The novel quad-band patch antenna includes complicated radiation mechanisms required for multiple-band operation. Two-port and four-port MIMO antenna systems that employ the quad-band patch antenna are proposed in the present work for the 5G mobile handsets. Numerical and experimental investigations are achieved to assess the performance of both the single-element antenna and the proposed MIMO antenna systems including the return loss at each antenna port and the coupling coefficients between the different ports. It is shown that the simulation results agree with the experimental measurements and both show good performance. The bandwidths achieved around 28, 45, 51, and 56 GHz are about 0.6, 2.0, 1.8, and 1.3 GHz, respectively. The radiation patterns produced when each port is excited alone are shown to be suitable for spatial diversity scheme with high radiation efficiency. It is shown that the envelope correlation coefficient (ECC) and the diversity gain (DG) are perfect over the four frequency bands.