Quad-band Compact MIMO Antennas for 5G Mobile Communications

Abstract

Three types of quad-band millimetric-wave two-port MIMO antenna systems are proposed for the forthcoming generations of mobile handsets. A novel printed antenna is introduced to be the single element of the proposed MIMO antennas. It is shown that the proposed MIMO antennas are capable of producing both spatial and polarization diversities that enhance the performance of mobile communications. Two configurations of co-polarized two-port MIMO antennas are proposed to provide spatial diversity, whereas a cross-polarized two-port MIMO antenna is proposed to produce polarization diversity. It is shown that all the proposed MIMO antennas can operate efficiently over the four frequency bands centered at 28, 43, 52, and 57 GHz. Prototypes are fabricated for the proposed MIMO antennas for the sake of experimental evaluation. The measurements agree with the simulation results showing high performance of the proposed types of MIMO antennas including the impedance matching, radiation patterns, envelop correlation coefficient, and diversity gain. Both the experimental and simulation results show that the achieved bandwidths, at the four operational frequency bands, are 0.6, 0.6, 1.8, and 1.5 GHz, respectively. Also, the radiation efficiencies calculated at the four operational frequencies are 86.5%, 87.5%, 89.2%, and 90.0%, respectively. The dimensions and the results concerning the performance of the proposed MIMO antennas are compared to other designs for MIMO antennas available in some recently published work.