Bandwidth Enhancement of High Gain Circularly Polarized Antenna for GNSS

Abstract

This work presents a detailed analysis of bandwidth enhancement through the transition from conventional circularly polarized (CP) crossed dipole antenna (CDA) to CP crossed bowtie dipole (CBD) antenna for GNSS applications. Inorder to justify fair comparison and practical suitability both the antennas are center fed with 50Ω coaxial cable and are backed by cylindrical cavity reflectors. Due to cavity reflectors, the crossed bowtie antenna supports extra resonant modes as well as attributes to impedance transition leading to broad impedance and axial ratio bandwidth. A detailed analysis for the proposed antenna is carried out indicating its bandwidth widening mechanism along with its simple feed mechanism. The conventional CDA achieves an impedance bandwidth of 11.3%(1.50-1.68)GHz and CP bandwidth of 8.8%(1.51-1.65)GHz which is enhanced in CBD antenna to 46.7%(1.01-1.77)GHz and 35.2%(1.05-1.50)GHz respectively. The gain is also enhanced from 7 dBic to more than 8.5 dBic in CBD antenna. These antennas are suitable for GNSS applications.