The OAM-based radar cross section and vortex mode characteristics of phase-modulated metasurface

In recent years, the scattering property of electromagnetic waves carrying orbital angular momentum (OAM) has drawn a lot of attention. We investigate the OAM-based radar cross section (RCS) and vortex mode characteristics of phase-modulated metasurfaces in this paper. The Bessel beams are adopted as the incident source and a chessboard metasurface as the target. Based on the array antenna theory, the scattering field of the metasurface is computed. Whereafter, the OAM-based RCS of the metasurface and the vortex mode of the scattering wave are obtained using the RCS theory and the Fourier transform, respectively. Compared to plane wave incidence, whose RCS is extremely low, the OAM-based RCS of the chessboard metasurface is obviously enhanced. In particular, for the l = ±2 case, the backscattering RCS is enhanced to a large extent, which reveals the anti-stealth ability of the OAM vortex waves. Moreover, the vortex mode modulation effect is also analyzed, which is helpful for the receiving and processing of the scattering echo.