Low RCS High-Gain Broadband Substrate Integrated Waveguide Antenna Based on Elliptical Polarization Conversion Metasurface

Designed an elliptical Polarization Conversion Metasurface (PCM) for Ka-band applications, alongside a high-gain Substrate Integrated Waveguide (SIW) antenna. The PCM elements were integrated into the antenna design in a chessboard array configuration, with the goal of achieving effective reduction in the antenna's Radar Cross Section (RCS). Both the PCM elements and antenna structure exhibit a simple and streamlined design. The top layer of the metasurface elements employs an elliptical pattern symmetric along the diagonal, enabling efficient conversion of linearly polarized waves. The antenna component, on the other hand, consists of a broadband dipole antenna fed by SIW slot coupling. Verified through simulations, the polarization conversion efficiency of this PCM reaches $80.38 \%$ within a bandwidth where the efficiency exceeds $90 \% \quad(25.3-59.3 \text{GHz})$, demonstrating exceptional conversion performance. When the dipole antenna is combined with the PCM, its −10 dB impedance bandwidth expands to $24.75 \%(30.8-39.5 \text{GHz})$, with a maximum realized gain of 9.68 dBi. Notably, the antenna loaded with the chessboard PCM structure effectively disperses the energy of scattered echoes around, significantly reducing the concentration of scattered energy in the direction of the incident wave, thereby achieving an effective reduction in RCS.