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In this paper, to achieve ultra-wideband radar cross section (RCS) reduction, a coding phase gradient metasurface (CPGM) is proposed by using Pancharatnam-Berry (P-B) phase. The CPGM is composed of eight types of CPGM elements, and a series of phase gradients with different directions or starting-values will be introduced in these types of CPGM elements under the same EM-wave incidence, so it can not only achieve anomalous reflection to reduce its specular RCS but also reduce the maximum bi-static RCS due to phase cancelation. The simulation results demonstrate that the CPGM has an excellent performance in RCS reduction, compared with a pure metallic plate with the same size, its specular RCS under normal incidence with arbitrary polarization can be reduced more than 10 dB in the ultra-wide frequency band of 8.8–34.8 GHz with a relative bandwidth of 119.3%, and its maximum bi-static RCS can also be reduced effectively in the ultra-wide frequency band; moreover, when the incident angle is increased to 45°, the RCS reduction can still be achieved in an ultra-wide frequency band. Finally, an effective experimental verification is carried out. [ABSTRACT FROM AUTHOR]

Because Pancharatnam-Berry (PB) geometrical phase can only be generated in the co-polarized reflection coefficient under circular polarized (CP) incidence for a reflective metasurface, the design of a reflective PB coding metasurface must be based on an appropriate polarization conversion metasurface (PCM) which can achieve CP-maintaining reflection. In this work, to design a reflective 2-dit PB coding metasurface for radar cross section (RCS) reduction, an ultra-wideband PCM is proposed at first, numerical simulation shows that the PCM can realize ultra-wideband CP-maintaining reflection from 8.6 to 35.9 GHz; moreover, PB phase will be generated in its co-polarized reflection coefficient under CP incidence by rotating its unit structure. Thus, an ultra-wideband reflective 2-dit PB coding metasurface is constructed successfully based on the PCM. The simulation and experiment results show that the coding metasurface has excellent performance in RCS reduction under arbitrary polarized incidences, compared with a pure metallic plate with the same size, its RCS can be reduced more than 10 dB in the frequency band 8.2–35.2 GHz with a relative bandwidth of 124.4%, in addition, the RCS reduction performance is kept well when the incident angle is increased to 45°. [ABSTRACT FROM AUTHOR]