Highly stretchable radar absorber based on kirigami metastructures with tunable electromagnetic properties

The demand for lightweight and multifunctional surface structure in high-end equipment is steadily growing. The harmonization between flexibility and electromagnetic tunability has become a significant subject for stealth morphing aircraft. This paper presents a microwave absorbing structure based on the kirigami configuration, aiming at improving the conformality with the negative Poisson’s ratio characteristic and expanding the radar stealth range with tunability. A precise electromagnetic reflectivity model of the impedance surface was established by the inversion method, and an integrated optimization algorithm was employed to optimize the structural parameters based on numerical analysis. Specimens composed of thermoplastic polyurethane elastic colloids and resistive materials were prepared to assess the in-plane mechanical tensile and electromagnetic absorption performances through experimental methods. The results indicate that the original absorption band spans 6.2–11.1 GHz, shifts to 8–18 GHz with stretching at a panel rotation angle of 16°, and remains nearly constant for further stretching. The specimens adhere to complex curved surfaces well in experiments and maintain the electromagnetic absorption performance compared with flat surfaces. This research offers a valuable reference for designing electromagnetic stealth structures that are highly stretchable and adjustable.