Low-Profile Wideband High-Gain and Low-RCS Circularly Polarized Array Using Checkerboard Polarization Rotators

In this paper, a circularly polarized (CP) array based on checkerboard polarization rotators (PRs) with wideband and low radar cross section (RCS) is presented. The proposed array is formed by $2 \times 2$ CP element antennas fed with a sequential feeding network. On the one hand, the CP array has a wide axial ratio (AR) bandwidth of 22.5% (AR $\leq$ 3 dB), an impedance bandwidth of 37.3% (S11 $\leq$ -10 dB), and a 3-dB gain bandwidth of 18.4% with a maximum of 13 dBic. On the other hand, the checkerboard arrangement of the PRs generates both an in-band and a partial out-band RCS reduction under normal incidence for both x- and y- polarizations.