A High Gain Wide Axial Ratio Beamwidth Circularly Polarized Antenna for L-band Phased Array Applications

This paper proposes a high gain circularly polarized antenna that can apply to a active electronically scanned array with a beam-scanning capability over a wide angle. The proposed antenna comprises the upper patch, metal columns, metal walls, and a coaxial fed lower patch. All metal structures of the proposed antenna are effectively grounded. The circularly polarized antenna in this article exhibits several noteworthy characteristics. Firstly, the presence of metal walls around the patch antenna forms a cavity structure, which improves the antenna's gain and helps to generate wide-angle circularly polarized beams. In addition, within the frequency range of 1.026GHz to 1.175GHz, the VSWR of circularly polarized antennas remains below 2. The antenna exhibits right-handed circular polarization, achieving an actual gain of 7.5dBi, while maintaining an axial ratio of less than 3 dB within the (−72.5 °, 80 °) range. It is indicated that the antenna has high gain and wide axial ratio beamwidth. Meanwhile, as all metal structures are grounded, it can effectively prevent the accumulation of negative charges on the antenna surface applied in space. Afterwards, the unit was rotated and fed to form a 21-element array, with an axis ratio below 2 in the 50 ° direction.