Microwave All-Dielectric Metamaterial Design of FeSiAl/MWCNT Composite for Low-Frequency Broadband-Absorbing Properties

FeSiAl flakes were fabricated by vibrating ball milling the FeSiAl ribbons. And the microwave absorption properties of FeSiAl flakes were improved by doping the multi-wall carbon nanotubes (MWCNTs) with different mass concentrations. The results show that the FeSiAl/MWCNT composites exhibit significantly improved microwave absorption performance with advantages of strong and broadband absorption in the L-band and S-band. In particular, the reflection loss (RL) of the FeSiAl/MWCNT2 composite reaches −7.4 dB at 1.0 GHz, whereupon, through the electromagnetic simulation software CST Microwave Studio, FeSiAl/MWCNT2 all-dielectric metamaterial absorbers (ADMMAs) were macroscopically designed, achieving an ultra-wideband absorption (RL ≤ −10 dB) of 14.4 GHz (3.6~18.0 GHz). It is recognized that the standing wavelength resonance and diffraction effect are responsible for absorbing electromagnetic waves, and the broadband absorption is improved via dielectric dispersion; their synergistic effect makes the ADMMAs exhibit good microwave absorption performance. This work provides a useful method for designing microwave absorption materials with broadband absorption.