Broadband Dual Circular Polarized Phased Array Antenna Using Hybrid Coupler

A broadband dual circular polarized (CP) antenna array achieving wide-angle scanning is proposed. The basic radiating structure is a dual orthogonal linear polarization (LP) banyan tree antenna with wideband and wide scanning performance. Combining the dual orthogonal LP antenna with a hybrid coupler that provides 90-degree port phase difference, the final dual-CP antenna array unit cell is realized. The simulation results of an infinite array show that the dual-CP antenna array works during 2GHz to 3.4GHz (relative bandwidth 52%) with VSWR < 1.5 at broadside and VSWR < 2.0 when scanning down to 40°, and the axial ratio is better than 2dB at broadside over the entire band.