Circularly Polarized Cross-Helix Antenna With Quasi-Hemispherical 3-dB Axial Ratio Coverage

This letter presents a circularly polarized (CP) antenna based on cross-helix with a wide 3-dB axial ratio (AR) coverage. First, a twin-helix is utilized to attain a symmetrically omnidirectional radiation pattern with circular polarization while maintaining a compact size. Then, by employing cross-arranged helices and a 90° hybrid coupler, a Huygens source with a wide CP radiation beam is realized. Additionally, a balun based on coaxial-wire and a λ/4 conductor strip is utilized to provide the differential feed signal. Simulation results reveal that the proposed antenna achieves a -10 dB bandwidth from 2.35-2.46 GHz. A very wide 3-dB AR beamwidth with ±90° in the two principal planes and at least ±75° in other cut-planes in the hemispherical space is obtained. The proposed antenna is fabricated and tested, and measured results are in good agreement with simulated ones. Characterized by the wide 3-dB AR spatial coverage, the proposed antenna exhibits great potential in wireless communication applications.