Spin-decoupled chiral metasurface antenna for simultaneous high-gain radiation and broadband low-RCS

Abstract Reconciling the mutual exclusivity between high-gain radiation and low radar cross section (RCS) remains a formidable challenge in the development of advanced stealth platforms. This paper proposes a novel chiral metasurface antenna(CMSA) designed to resolve this paradox by effectively decoupling scattering suppression from radiation enhancement within a single planar aperture. Drawing inspiration from the chiral asymmetry found in nature, the proposed unit cell incorporates lumped resistors into chiral split-ring resonators (SRRs) to engineer a distinct spin-selective electromagnetic response. Specifically, the metasurface acts as a dissipative absorber for incident right -handed circularly polarized (RCP) waves, converting the electromagnetic energy into heat via ohmic loss to minimize backscattering. Conversely, it functions as a highly efficient reflector for left-handed circularly polarized (LCP) waves, thereby supporting high-gain radiation when excited by a feed network. Experimental validation of a fabricated prototype demonstrates the efficacy of this design: in the scattering mode, a broadband RCS reduction of over 5 dB is achieved across the 8-13 GHz frequency range under RCP illumination; in the radiation mode, the antenna exhibits a peak gain of 21.3 dBi at 10.6 GHz with a wide 3-dB axial ratio bandwidth. By achieving simultaneous low observability and highperformance radiation on a passive, compact structure, this work offers a promising solution for next-generation integrated RF stealth systems.