A Compact Wideband Circularly Polarized Magneto-Electric Dipole Antenna Array for 5G Millimeter-Wave Application

A compact wideband circularly polarized (CP) magneto-electric (ME) dipole antenna array is proposed. In order to achieve compact size and wideband characteristics, a novel substrate integrated waveguide (SIW) to coaxial transition (SCT) was designed to connect the lightning-shaped ME-dipole antenna element and an SIW feeding network. Particularly, an SCT-based power divider network together with the sequential-rotation (SR) technique was employed to improve the axial ratio (AR) bandwidth of the 4×4 antenna array. The antenna array prototype was fabricated to verify the design. Measured results show that an impedance bandwidth of 27.7% (23.3-30.8 GHz) and 3 dB gain bandwidth of 25.3% (23.5-30.3 GHz) were achieved. Moreover, a 3 dB AR bandwidth of 27.8% (23.2-30.8 GHz) with a peak gain of 20.2 dBic was also recorded. Therefore, it is a good candidate for the fifth-generation (5G) millimeter-wave (mm-wave) communications.