An ultra-wideband coding phase gradient metasurface for RCS reduction

In this work, an ultra-wideband coding phase gradient metasurface (CPGM) is proposed for radar cross section (RCS) reduction. The design process is presented in detail, in which eight types of coding elements are proposed firstly by using Pancharatnam-Berry (P-B) phase. The eight types of coding elements have different reflection direction or phase response under the same EM-wave incidence for they can introduce a series of phase gradients with different directions or starting-values under both right-handed and left-handed circular-polarized incidences, so the proposed CPGM composed of these coding elements has excellent performance in RCS reduction. The simulated results show that, compared with a pure metallic plate with the same size, the RCS of the CPGM can be reduced more than 10 dB in the ultra-wide frequency band of 9.2-46.2 GHz under normal incidence with arbitrary polarization, the relative bandwidth is up to 133.6%; moreover, the RCS reduction under oblique incidence with arbitrary polarization can still be kept larger than 9.3 dB in the frequency band of 13.1-42.5 GHz when the incident angle is increased to 45 degrees. Finally, one experiment is carried out, a reasonable agreement exists between the simulated and experimental results.