Effective broadband electromagnetic wave absorption performance of nano-Fe3O4 magnetic fluid-modified resin geopolymer by metamaterial with a novel patterned structure

Abstract

It is challenging to achieve high-strength absorption and effectively broaden the absorbing bandwidth when using conventional flat microwave-absorbing cementitious materials. To address this challenge and achieve excellent microwave-absorptive performance, this study proposes a novel two-layered periodic stepped absorbing structure (PSAS) composed of a mixture of nano-Fe3O4 magnetic fluid and a resin geopolymer. Additionally, the incident angle-dependent absorption performance, the impact of geometrical parameters, and the shape of the unit cell were investigated. The results demonstrate that the absorption of the designed metamaterial absorber exceeds 90% in the total frequency range of 2–18 GHz. A mean reflection value of −18.3 dB was obtained in this study. The outstanding absorption performance of PSAS results from the cooperative effect of multiple λ/4 resonances and edge diffraction effects, which improve the impedance matching to the level of the free space in a broad frequency domain. Combining the effect of electromagnetic field regulation with metamaterial structure, the ultra-broadband absorption can be significantly enhanced by adjusting the geometrical parameters of the unit cell for absorption resonance.