A compact wideband two-port MIMO antenna with intrinsic feed-based decoupling for 26–32 GHz 5G millimeter-wave applications

Abstract In this paper, a miniaturized wideband dual-port MIMO antenna operating at 26.3–32 GHz millimeter-wave band is designed for future-generation 5G wireless communications. The antenna is fabricated on a RO3210 substrate and comprises two identical stepped-slot loaded radiators placed symmetrically, without the need for any additional decoupling network. A distinctive aspect of the design is the use of a non-uniform feed line which ensures controlled transition of impedance and phase to realize broadband impedance matching, and mutual coupling suppression. In such a way, the antenna attains a measured impedance bandwidth from 26.3 to 32 GHz with − 10 dB return losses. Isolation between the ports stays under − 15 dB through out the operating band, and even drops to − 25 dB–30 dB during resonance frequencies. Broadside radiation patterns and a measured realized gain of 7.5–8.5 dBi together with a simulated directivity of 11–12 dBi have been observed. These high values of directivity are achieved because of constructive interference at millimeter wave frequency. The diversity performance study reveals that envelope correlation coefficient is below 0.01 (from S-parameters) and below 0.02 (from far-field patterns), diversity gain is approximately 10 dB, the channel capacity loss stays below 0.35 bps/Hz, and a well-balanced mean effective gain lies within − 3.5 dB and − 4.2 dB. Because of its miniaturized size of 10.9 × 13 mm², wide impedance bandwidth, and excellent isolation, MIMO performance of this antenna is considered suitable for integration in compact 5G millimeter-wave user equipment and multi-antenna communication devices.