Design of circularly polarized antenna with wide overlapped axial‐ratio and gain beamwidths for upper hemispherical coverage

Abstract

AbstractIn this letter, a circularly polarized antenna with wide overlapped axial ratio and gain beamwidth is proposed for upper hemispherical coverage. By bending half of the dipoles to the vertical direction, and connecting eight metal columns to the ground, the half‐power beamwidth (HPBW) of all cut planes can be increased effectively. On the basis, one reactive impedance structure is applied as the reflector to achieve unidirectional radiation, as well as increase the 3‐dB axial ratio beamwidth (ARBW) of the antenna. Miniaturized four‐feed networks are utilized to provide excitation, and the shielding technique is applied to reduce its influences on the antenna radiation performances. Measurements show that the proposed antenna can operate in the range of 1.51–1.59 GHz, which covers the upper band of global navigation satellite system (GNSS). Besides, at 1.561 GHz, the measured HPBWs and 3‐dB ARBWs are larger than 131° and 135° in all cut planes. The wide overlapped beamwidth of the proposed antenna with small size indicates the potential applications in high‐precision GNSS navigations.