Cascaded Broadband Low-Frequency Microwave Absorption Covering P- to C-Band in Ultra-Thin Metamaterials via...

Low-frequency radar waves, particularly in the P-band, present a significant stealth challenge due to the inherent trade‑offs among strong absorption, broad bandwidth, and ultra-thin thickness. These limitations arise from the conflict between structural thickness and wavelength, impedance-matching difficulties, and weakened loss mechanisms. To overcome these constraints, a new strategy for synergistic enhancement of the local field and electromagnetic loss field of metamaterials has been proposed. By employing metasurface structures for local‑field enhancement, strong absorption is achieved at ultra-thin thicknesses. Furthermore, dielectric, magnetic, conduction, and structural resonance losses are integrated to enable strong, broadband absorption. Herein, a double-layer metasurface array is designed and integrated onto a polydimethylsiloxane/flake carbonyl iron high‑loss dielectric substrate. The resulting composite exhibits exceptional performance in the 1.77-2.85 GHz range at a thickness of only 3.78 mm (~ 0.022 λ), with an absorption rate exceeding 90%, and the absorption rate within the 1-6 GHz range can exceed 60%. It also demonstrates good mechanical flexibility and stability. The proposed local‑field enhancement principle provides a new route to bypass the quarter-wavelength limitation of traditional absorbers, while its ultra-thin, broadband, and flexible integrable features highlight its potential for efficient conformal integration on complex curved surfaces.