1：Experimental Design and Method Selection:

A compact anisotropic meta-atom is optimized with reflection phases independently controlled upon x-and y-polarized incident EM wave. An integrated phase profile is utilized to convert the y-polarized spherical wavefront into a vortex spiral counterpart, while a checkerboard-like phase profile is employed to destroy the plane wavefront of x-polarized incidence so as to reduce the backward RCS for x-polarization.

2：Sample Selection and Data Sources:

The designed metasurface consists of 22 × 22 elements and thus occupies a size of

3：6 × 6 mmList of Experimental Equipment and Materials:

1 Copper thin film with a thickness of

4：036 mm is used to form the top metallic pattern and the ground plane, while the dielectric layer is with relative permittivity of 65 and loss tangent of Experimental Procedures and Operational Workflow:

The metasurface is illuminated by x-polarized plane wave to investigate its scattering characteristic, and then is impinged by spherical wave emitted from the focal spot to generate vortex beam carrying OAM.

5：Data Analysis Methods:

The performance of RCS reduction is analyzed by comparing the backward RCS reduction of the designed MS with a same-sized metallic plate under normal incidence. The vortex beam conversion efficiency is evaluated by detecting peak and zero-depth value.