Wideband Circularly Polarized Quadrifilar Helix Antenna With Hemispherical Coverage

This paper presents a wideband circularly polarized quadrifilar helix antenna (QHA) featuring simultaneously wide 3-dB axial ratio beamwidth (ARBW) and half-power beamwidth (HPBW), addressing the conventional trade-off between bandwidth and beamwidth. The antenna comprises four pairs of three- stage stepped-impedance folded helical arms, collectively loaded with an arc-shaped metal ring on top. The three-stage stepped-impedance folded helical arm effectively enhance the bandwidth while maintaini