Compact Crossed-Dipole Antenna Design With Wide Axial Ratio Bandwidth and Unidirectional Gain for 5G Sub-6 GHz Applications

This communication presents a novel technique that miniaturizes a crossed-dipole antenna (CDA) while simultaneously maintaining a wide axial ratio (AR) bandwidth performance. The strategy of asymmetrically truncating one arm of the dipole achieves a 50% reduction in the dipole size. However, the dipole arm truncation caused the antenna to lose its circular polarization characteristics. To restore the circular polarization, two radiating longitudinal stubs are integrated into the antenna. In addition, the design includes a protruding stub to shift the operating frequencies of the 3-dB AR to sub-6-GHz bands. The unidirectional gain is achieved by positioning a reflective cavity below the antenna. Measurements revealed a 3-dB AR bandwidth ranging from 3.34 to 5.18 GHz and an average gain of more than 5 dBic, thereby covering the sub-6 GHz of 5G new radio (NR) bands.