Ultrabroadband Low‐Frequency Microwave Absorption in Multiscale Aerogel‐Metamaterial Hybrids

ABSTRACT The increasing demand for lightweight electromagnetic wave (EMW) absorbing monoliths, particularly those capable of absorbing both low‐frequency and broadband EMWs, presents a significant challenge. While dielectric nanostructured aerogels have demonstrated high potential and advancements, a gap remains in the development of aerogel‐based EMW absorbers to achieve effective low‐frequency and broadband absorption. Here, we present a multiscale engineering strategy for fabricating aerogel‐metamaterial hybrids, addressing key challenges such as broad bandwidth, low‐frequency absorption, and high load‐bearing capacity. The proposed absorber consists of a simulation‐assisted additive‐manufactured thin‐walled enclosure embedded with graphene/nanocellulose aerogels, which feature an effective conductive network and abundant heterogeneous interfaces. This multiscale design enables exceptional EMW absorption across the entire 2–18 GHz band, achieving 100% bandwidth coverage, with stable performance under wide oblique incidence (up to 60°) and polarization (both transverse electric and transverse magnetic). Furthermore, the absorber exhibits a low areal density of 2.714 kg m ⁻² and can withstand at least 95 kg of out‐of‐plane load. These advancements highlight the potential for developing lightweight, novel EMW‐absorbing aerogel metamaterials for low‐frequency, ultrabroadband electromagnetic compatibility and aerospace applications.