A Wideband Wide-Beam Circularly Polarized Antenna for GNSS Applications

A broadband circularly polarized (CP) antenna for global navigation satellite system (GNSS) applications is proposed in this paper. The antenna adopts a modified crossed bowtie dipole with a ground-loaded fence metal-backed cavity. The bowtie dipole arms and the phase delay line are etched as a gradient configuration, altering the current path by introducing discontinuous segments, and the axial ratio (AR) performance is improved primarily. A ground-loaded fence metal cavity is introduced to largely improve the AR bandwidth especially in the low-frequency band. Meanwhile, a miniaturization is achieved. Because of the electromagnetic coupling on the grating structure of the fence, the beamwidth is broadened. The overall size of this antenna is $0.39 \lambda_{0} \times 0.39 \lambda_{0} \times 0.26 \lambda_{0}$ ($\lambda_{0}$ is the wavelength of the center frequency). The antenna shows an impedance bandwidth of 78.8% for VSWR >2(0.93 GHz-2.14 GHz), axial-ratio bandwidth of 54.6%(1.13 GHz-1.98 GHz), and the half-power beamwidth of greater than 105° in simulation. The proposed antenna exhibits stable right-hand circular polarization (RHCP) radiation patterns, making it promising for applications in satellite communication systems.