Design of Wideband Circularly Polarized Antenna Using Coupled Rotated Vertical Metallic Plates

A simple structure composed of four rotated metallic plates is proposed to enhance the bandwidth of circularly polarized (CP) crossed-dipole antenna. The metallic plates are vertically added on the ground plane in a sequential rotation way, surrounding the primary radiator of the crossed-dipole antenna. Owing to the coupling with the radiator, orthogonal currents can be induced on the metallic plates. Additional impedance and axial ratio passbands can, therefore, be generated beside the original operating band, enhancing its bandwidth substantially. As the metallic plates are mounted on the ground plane, no extra footprint is needed, making the area of the wideband antenna very compact. Simulation and measured results show that by using this simple structure, the operating bandwidth of CP crossed-dipole antenna can be enhanced significantly from ~30% to 106.1%. The structure is also applicable to the intrinsically narrowband patch antennas.