A Low-Profile, Dual-Polarized Patch Antenna for 5G MIMO Application

A dual-polarized patch antenna with an extremely low profile is proposed in this communication. It consists of a main radiator, an annulus, and a reflector. The main radiator contains two pairs of differentially driven feedlines and an irregular patch. These differentially driven feedlines are utilized to coupled feed the irregular patch through a small gap, which has distinguished feature compared with other designs. It turns out that a resonance at 3.55 GHz is generated. Then, an annulus is set above the main radiator to compensate the inductive component induced by the main radiator and generate the other resonant point. As a result, the dual-polarized antenna could work from 3.3 to 3.6 GHz with the extremely compact size of 0.29 lambda(0) x 0.29 lambda(0) x 0.06 lambda(0). (lambda(0) is the free-space wavelength at 3.45 GHz.) The simulated isolation and cross-polarization discrimination at 0 degrees of the antenna element reach more than 35 and 44 dB. The simulated front-to-back ratio of co-polarization and cross-polarization is larger than 44 and 22 dB, separately. To verify the design, a prototype of the 2 x 2 array based on the element is fabricated and measured. The results show that the antenna has high potential in the fifth-generation (5G) massive multiple-input multiple-output application.