Four-port dual CP MIMO antenna with enhanced isolation for 5G applications

In this paper, a 4 x 4 MIMO (multiple-input multiple-output) antenna with metasurface (MS), which is composed of dual circularly polarized (CP) patch antennas, is proposed for 5G (sub-6 GHz) applications. The MIMO antenna consists of four microstrip patch antennas. In order to improve the isolation of the MIMO antenna, parasitic elements are placed on the MS and layer of patch antennas. In addition, a substrate-integrated waveguide (SIW) structure is used at the center of the MIMO antenna for this purpose. The proposed MIMO antenna is fabricated for validation tests. The antenna has overall dimensions of 115 mm x 115 mm x 3.2 mm (1.219 lambda 0$$ {\lambda}_0 $$ x 1.219 lambda 0$$ {\lambda}_0 $$ x 0.033 lambda 0$$ {\lambda}_0 $$, where lambda 0$$ {\lambda}_0 $$ is the free space wavelength at the lowest operating frequency in 10-dB impedance bandwidth). The MIMO antenna has 10-dB impedance bandwidth (IBW) from 3.3 to 3.8 GHz (14.08%), 3-dB axial ratio bandwidth (ARBW) from 3.42 to 3.69 GHz (7.59%), and 6.36-dBi peak gain. The isolation is greater than 28.14 dB in the n78 frequency band (3.3-3.8 GHz). A new type of dual circularly polarized four-port MIMO microstrip patch antenna with metasurface is proposed to obtain high isolation for 5G applications. Substrate-integrated waveguide structure and parasitic elements are used together to obtain high isolation for circular polarization. Theoretical and measurement results show that the proposed antenna can be effectively used for 5G applications. image