A broadband circularly polarized magneto-electric dipole array antenna for 5G millimeter-wave applications

A millimeter-wave (mm-wave) broadband circularly polarized (CP) magneto-electric (ME) dipole array antenna is proposed. The antenna element consists of a ME dipole, a direct T-shaped probe, and a pair of shorted parasitic elements. The shorted parasitic elements are employed to ensure a considerable expansion of the 3 dB axial ratio (AR) bandwidth to lower frequencies. As a result, the ME dipole antenna element achieves a wide overlapped AR/impedance bandwidth of 56.89% (22.45-40.3 GHz). Based on the proposed CP antenna element, a 2 × 2 CP array antenna that incorporates an improved X-shaped power divider network is developed. A prototype of the 2 × 2 CP array antenna is fabricated and experimentally verified. The measured results indicate that a −10 dB impedance bandwidth of 50.39% (23.9-40 GHz) and a 3 dB AR bandwidth of 50% (24-40 GHz) are achieved, forming a broad overlapped AR/impedance bandwidth of 24-40 GHz, which covers most of the current mm-wave 5G bands. Moreover, a peak gain of 14.88 dBic is also observed. Thus, the demonstrated antenna with broadband CP operation and good radiation performance can be an excellent candidate for 5G mm-wave applications.