Dual-Control strategy of structure and polarization for tunable electromagnetic wave absorption in the S-Ku band

The design of efficient electromagnetic wave absorbers must account for the specific frequency ranges encountered in application scenarios. This study adopts a dual-regulation strategy involving structural and polarization control to enable carbon matrix to effectively absorb electromagnetic wave across diverse frequencies. Sodium silicate modified activated carbon (SMA) composites were synthesized through hydrothermal and calcination process. By integrating experimental investigations with computational simulations, the effects of sodium silicate content on the structural and polarization characteristics of the composites were comprehensively analyzed. The SMA composites exhibited outstanding absorption performance across multiple frequency bands, with minimum reflection loss values of −47.68 dB in the S-band, −58.3 dB in the C-band, −54.62 dB in the X-band, and −61.04 dB in the Ku-band. Importantly, the study unveiled a novel frequency-tuning mechanism for designing high-performance EMW absorbers. Density functional theory calculations revealed that sodium ion intercalation induces charge redistribution within carbon layers, resulting in significant dipole polarization under low-frequency EMWs. Meanwhile, the dispersed silicates within the carbon matrix promoted multiple interfacial polarization effects, enhancing high-frequency absorption capabilities. This work establishes a cost-effective and versatile approach to designing frequency-adjustable, high-efficiency EMW absorbers, offering substantial advancements for practical applications in electromagnetic compatibility, radio-frequency identification, and wireless communication systems.