Broadband and dual circularly polarized patch antenna with H-shaped aperture

A dual circularly polarized (CP) patch antenna design with H-shaped aperture in S band is presented. The dual H-shaped slots are placed in orthogonal direction, and excited by the 3-dB branch-line coupler to obtain both right hand circular polarization (RHCP) and left hand circular polarization (LHCP). According to our simulation results, the proposed antenna element could achieve -10dB-level fractional impedance bandwidth around 17% without the 3-dB branchline coupler, and around 32.6% with the 3-dB branch-line coupler for the dual circular polarizations, respectively. The antenna element broadside gain is 5.15 dB and the cross-polarization level is lower than -37 dB for dual circular polarizations. The axial ratio (AR) below 3dB is more than 180° in both phi=0° and phi=90° planes in each circular polarization state. And the AR fractional bandwidths are, respectively, 29% when the Co-polarization is RHCP, and 33% when the Co-polarization is LHCP. Moreover, the main beam of the dual circular polarizations of the proposed 1 × 8 linear phased array has a very wide scanning coverage in phi=90° plane (i. e., from -45° to 45°, when AR <; 3 dB).