The Design of Broadband Circularly Polarized Multi-beam Antenna with Linearly Polarized Feeding Source and Transmitarray Unit

Abstract

Among the existing circularly polarized multi-beam transmitarray antennas, circularly or linearly-to-circularly polarized transmitarray units are always required. Naturally, designing circularly polarized units is more challenging than linear polarization. To simplify design and increase operation bandwidth, a novel method using linearly polarized transmitarray units and feeding sources is proposed for designing the circularly polarized multi-beam antenna. Broadband circular polarization is realized by utilizing sequential rotation technology and 1-bit phase compensation of linearly polarized transmitarray units. Meanwhile, beam scanning is achieved by using linearly polarized feeding sources offset. To validate the design, two multi-beam antenna samples are demonstrated. Simulated and measured results show that the designed multi-beam transmitarray antennas can realize beam scanning to 0°, ±10°, and ±20° in E-plane and H-plane. Moreover, two antennas maintain -10-dB impedance bandwidth and 3-dB axial ratio (AR) bandwidth at 8.5-10.4 GHz and 8.5-10.5 GHz, respectively. The proposed circularly polarized multi-beam transmitarray antennas have the advantages of broadband operation, simple design, and low cost.