Strong Magnetic–Dielectric Synergistic Gradient Metamaterials for Boosting Superior Multispectral Ultra‐Broadband Absorption with Low‐Frequency Compatibility

Abstract The construction of 3D porous structures and metamaterials (MMs) is the most promising approaches to achieve broadband electromagnetic wave (EMW) absorption. However, it is still a huge challenge to achieve multispectral ultra‐broadband EMW absorption properties compatible with low‐frequency band (L‐ and S‐band) due to its ultralong wavelength and strong bypass capability. Herein, magnetic–dielectric synergistic gradient MMs (MDSGM) consisting of oriented flaky carbonyl iron (FCI) film and periodical RGO/CNT/CNF aerogel (GTFA) array are demonstrated. Benefiting from the synergistic effect of strong magnetic–dielectric loss, structural loss, and excellent impedance matching, MDSGM harvests an exciting multispectral ultra‐broadband EMW absorption performance with a remarkable effective absorption bandwidth covering the whole measured frequency of 1–40, 50–110 GHz, and 0.1–2.0 THz for the first time. The minimum RL ( RL min ) reaches −40.24 dB and average RL is up to −19.3 dB (98.8% EMW being absorbed) in microwave band. Moreover, this multispectral ultra‐broadband EMW absorption property is less affected by the incident angle. This work pioneered realization of multispectral ultra‐broadband EMW absorption compatible with low‐frequency, which provides a great thrust for the development of stealth technology in the upcoming smart era.