Hybrid Metasurfaces With Cubic and Vortex Phase Distributions for Broadband RCS Reduction

Based on the inspiration of Airy beam and vortex beam, this paper proposes an efficient and formulaic method to achieve radar cross section (RCS) reduction for broadband and wide angle. We combine cubic phase and vortex phase to directly and efficiently calculate the phase distribution of each element of the metasurface, which reduces the time-consuming steps of traditional optimization design methods and saves a lot of computer resources and time. In addition, it is only necessary to consider the position of the metasurface elements, without the need to account for the wavelength. This approach facilitates the potential scalability of frequency bands. An arc I-shaped unit was designed, achieving a reflective phase range of 0° to 360° through the rotation of the unit cell, which served as a basis for example verification. Both simulation and experimental outcomes indicate that when plane waves irradiate on the metasurface at different angles, the designed metasurface is capable of significantly reducing the RCS and achieving a diffuse reflection mode. Within the 7-28 GHz frequency range, the bandwidth for a minimum of 10dB RCS reduction reaches up to 90%. Moreover, under oblique incidence conditions, the metasurface maintains excellent angular stability, achieving a 10dB RCS reduction at both azimuth and elevation angles of 60°.