Design of composite stealth cloak based on anomalous reflections and vortex singularities

In this paper, an ultra-thin (0.072λ) composite stealth cloak is proposed to cover a cloak with a center height of 98.88 mm and an inclination angle of 25° to achieve the dual stealth effect of scattering and gain. Firstly, based on the Generalized Snell theorem, the designed anomalous reflective metasurface has been shown to have a good invisibility in the 14–30 GHz region in simulations as well as in experiments. Secondly, the 3-bit metasurface unit is utilized to generate vortex beams with different number of modes, whose electric field strength at the vortex singularity is 0, which achieves energetically stealth. Finally, the phases of the above two metasurfaces are superimposed using the convolution theorem, and the designed composite stealth cloak significantly reduces the scattering amplitude and reconstructs the wavefront over a wide frequency range when a circularly polarized wave is incident vertically. Based on the above study, the stealth cloak provides a feasible solution for application to radar and microwave antenna stealth systems.