A 2-Bit Absorptive Pancharatnam-Berry Coding Metasurface for RCS Reduction

This article initially presents a circular polarization conversion metasurface (CPCM) with lossy characteristics, which exhibits a certain level of wave-absorbing capability due to ohmic loss. Critically, it enables ultra-wideband circular-polarization (CP)-keeping reflection, allowing the reflection phase under CP incidence to be freely adjusted through the Pancharatnam-Berry (P-B) phase generated by rotating its unit structures. Thus, based on the lossy CPCM, the article furtherly proposes a 2-bit absorptive P-B coding metasurface (CMS) specifically designed for radar cross-section (RCS) reduction. The simulation and experimental results demonstrate that the absorptive P-B CMS can reduce its RCS effectively in the ultra-wide frequency band from 7.0 to 42.2 GHz under vertical incidence with arbitrary polarization, and the relative bandwidth is up to 143.1%; furthermore, the ultra-wideband RCS reduction remains effective even for the oblique incident angle up to 45°, which indicates the potential application of the absorptive P-B CMS in radar stealth technology.