Reconfigurable Metasurface Based on Shape Memory Alloy Actuators for Ultra-Wideband RCS Reduction

Abstract

Reconfigurable metasurfaces exhibit remarkable capabilities in suppressing radar scattering signatures, but their effectiveness is often constrained by a single modulation mechanism. This work proposes an ultra-wideband radar cross section (RCS) reduction metasurface based on height-tunable absorbing unit cells actuated by shape memory alloy (SMA) springs. This design integrates a three-layer lossy absorber for broadband low-frequency absorption with dynamic phase modulation of sub-blocks, achieving frequency-controllable scattering manipulation through phase cancellation. By electrically tuning the bias voltages applied to the SMA springs, the metasurface can switch among strong absorption, frequency-tunable scattering, and ultra-wideband RCS reduction states. Experimental results show a broadband high absorption in the range of 4–12 GHz, while height tuning of the SMA-actuated elements enables frequency-controllable RCS reduction from 16.1 to 36.3 GHz. In the integrated state, a superior 20 dB RCS reduction is achieved across 4.2–40 GHz. Moreover, the metasurface maintains robust performance under wide-angle incidence and different polarizations, demonstrating great potential for adaptive scattering control and dynamic camouflage applications.