Choke Ring Loaded Crossed Dipole Antenna with Low Multipath Effects

Abstract

This paper presents a compact single-fed circularly polarized (CP) wideband crossed dipole antenna (CDA) integrated with dual corrugated conical shaped choke rings on a circular flat ground plane for Global Navigation Satellite Systems (GNSS) applications. These choke rings help to mitigate multipath propagation effects thereby reducing the sidelobes and backlobes. The proposed antenna can achieve an impedance bandwidth of 77.3% (1.00-2.26) GHz for S11 ≤ -10 dB and axial ratio bandwidth of 60.7% (1.10-2.06) GHz for AR ≤ 3 dB ensuring better polarization purity. The single-fed CDA is placed on a circular substrate having a radius of 0.2λ at a height of 0.27λ (where λ is the wavelength at lowest CP frequency). The conical shaped concentric rings suppress multipath components by enhancing the cross polar difference of more than 15 dB to avoid positioning error in GNSS antennas. The antenna achieves a 3 dB AR beamwidth higher than 75o with a stable gain of more than 7.8 dBic across all operating bands.