Dual-Polarized Ring-Slot 5G Millimeter-Wave Antenna and Array Based on Metal Frame for Mobile Phone Applications

In this paper, a dual-polarized ring-slot 5G millimeter-wave antenna and its array are proposed. The antenna consists of a cavity-backed ring-slot and two micro-strip feeding branches which are mutually orthogonal. The ± 45° dual polarizations are obtained by coupled feeding the ring-slot with the two feeding branches. The -10dB impedance bandwidth of the proposed antenna is from 27.5GHz to 28.35GHz. The realized gain is 4.86dBi and the difference between the co- and cross-polarized levels is better than 15dB at 28GHz. For a 1×8 linear array based on the proposed antenna element, the realized gain and side lobe level of the array in the two polarizations are pretty good, when the scanning angle varies from 0 degree to 50 degrees. The proposed antenna array can be integrated with the metal frame of handset devices, which can achieve good end-fire radiation at the same time.