Fishing net-inspired broadband tunable microwave absorbing metamaterial with minimal mechanical actuation stroke

The increasing complexity of electromagnetic (EM) environments has intensified the demands for dynamically tunable microwave absorbing metamaterials (MAMs). However, challenges such as high fabrication costs, large mechanical actuation strokes, and restricted tuning capability have hindered the practical applications of tunable MAMs. Inspired by fishing nets, this study proposes a mechanically actuated tunable MAM that achieves adjustable EM absorption through vertical movement of an inductive metallic plate within an uncured carbonyl iron powder/epoxy resin composite. By combining equivalent circuit theory and genetic algorithm optimization, the structure achieves broadband effective absorption from 6.25 to 40 GHz with a thickness of only 3.34 mm. With a minimal actuation stroke of 2.9 mm, the effective absorption band expands to cover the full 2–40 GHz range. Furthermore, the continuous tunability of the MAM enables wideband absorption coverage even under oblique incidence. The broadband absorption performance originates from the synergistic interaction between the magnetic material (MM) and the resistive film, while the tunability is primarily attributed to modulation of the EM path length via control of the MM thickness. The proposed tunable MAM, featuring an ultra-broad bandwidth, a minimal mechanical actuation stroke, and continuous tunability, demonstrates significant potential for practical applications.