A novel combination-type electromagnetic gradient metasurface for specular RCS reduction

Electromagnetic Gradient Surface (EGS) has attracted considerable attention due to its unusual physical characteristics, showing great potential in radar cross section (RCS) reduction. In this paper, we provide a new approach to reduce radar cross section at boresight and present a design example of a novel hybrid electromagnetic gradient metasurface, which appears as a single sandwiched structure and is composed of a patterned metal square patch layer with variable sizes as the reflecting elements and a metal ground plane separated by a dielectric spacer The proposed metasurface is capable of suppressing the specular reflected wave by more than 17.5 dB under vertical polarization and 12.5 dB under horizontal polarization. More than 10 dB RCS reduction with bandwidth of nearly 1 GHz in a wide range of incident angle is realized at two polarizations effectively. Numerical simulation validates that this metasurface can redirect the scattered wave by adjusting the phase gradient and realize the specular RCS reduction, which shows great application potential in the area of radar anti-detection and exhibits a promising and flexible method to control the propagation of the EM wave.