A Compact Dual-Sense and Dual-Band Circularly Polarized Antenna With Wide Axial-Ratio Beamwidth for BeiDou navigation satellite system

This paper presents a dual-sense circularly polarized (CP) antenna with a low-profile and wide axial-ratio (AR) beamwidth for the BeiDou navigation satellite system. The proposed antenna consists of two layers of patches, and the dual-band characteristics are achieved by using a single coaxial probe to feed two layers of patches simultaneously. Two pairs of orthogonal rectangular slots and diagonal truncations are etched on the patches, separating two pairs of degenerated modes to achieve RHCP in the high frequency band and LHCP in the low frequency band, realizing dual-sense operation. By selecting suitable slots and truncations, the far-field electric field can be orthogonal with equal amplitude and phase difference (close to 90°) in a wide angle range, realizing a wide AR beamwidth. The impedance bandwidths are 3% and 2.8%, and the 3dB AR bandwidth is 0.6% and 0.8%. In the 1.615GHz and 2.492GHz bands, the AR beamwidths in the two main planes are greater than 120°, and the AR beamwidths in four radiation planes are greater than 100°. The HPBWs of four radiation planes are greater than 80° and the peak gains are 6.8 dBi and 7.3 dBi.