High Electromagnetic Waves Absorbing Performance of a Multilayer‐Like Structure Absorber Containing Activated Carbon Hollow Porous Fibers–Carbon Nanotubes and Fe 3 O 4 Nanoparticles

Carbon nanotubes (CNTs) are grown on the surface of activated carbon hollow porous fibers (ACHFs) by chemical vapor deposition. A multilayer‐like structure absorber ACHFs–CNTs–Fe 3 O 4 is prepared when Fe 3 O 4 nanoparticles/epoxy resin are injected into the hollow structure of ACHFs. Microwave reflection loss, permittivity, and permeability of ACHFs–CNTs–Fe 3 O 4 in 2–18 GHz are measured. The results show that the minimum reflection loss of ACHFs–CNTs–Fe 3 O 4 has reached to −46.828 dB at 14.4 GHz with the thickness of 2.5 mm, and the bandwidth below −10 dB can be as broad as 7.2 GHz. A wide effective absorbing bandwidth can be 13.54 GHz with the variation of the sample thickness from 1.5 to 5.0 mm. The low minimum reflection loss may result from electromagnetic coupling effect of ACHFs, CNTs, and Fe 3 O 4 nanomagnetic particles. The broad absorbing bandwidth is ascribed to its special multilayer‐like structure.