Integrated Multilayer Sandwich-Type Tunable Absorbing Composites for Wideband Radar Cross Section Control

This letter presents a tunable absorbing composite that integrates a varistor-diode-based ultrathin impedance layer into a lightweight sandwich structure for broadband and continuously programmable RCS control. A theoretical equivalence model is established and reveals that the tunable layer emulates multiple resistance states. Based on this mechanism, the metasurface achieves amplitude-coded RCS control through the spatial arrangement of the 40$\Omega$, 60$\Omega$, and 80$\Omega$resistive states, in contrast to conventional phase-coded approaches. Experiments verify flexible up to 10 dB RCS reduction over 6–13 GHz, demonstrating a scalable route toward adaptive electromagnetic protection materials.