Search

Broadband microwave absorbing materials with a multilayer structure based on multi-walled carbon nanotubes (MWCNTs) as a filtering layer has been designed. The absorption curves of the multilayer structure change from a single peak to double peaks after the addition of the filtering layer. As a result, the effective microwave absorption bandwidth is broadened to 12.6 GHz with a total thickness of 2.3 mm. Normalized power flow and power loss distribution maps at fixed frequencies were analyzed by CST simulator. The broadening of the microwave absorption bandwidth is attributed to the electromagnetic wave selective filtering effect of the MWCNTs which contribute to impedance matching and microwave absorption at different frequencies.

Microwave absorption composites consisting of Ce2Fe17N3-δ and various weight ratios of multi-walled carbon nanotubes (MWCNTs) (0, 0.5, 1, 1.5 wt%) as absorbers were prepared, and their microwave absorption performance was investigated. The results show that the composites attain increasing complex permittivity as the loading ratio of MWCNTs increase, whereas the permeability is almost unaffected. The composite filled with 0.5 wt% of the MWCNTs had a minimum reflection loss (RL) of −48.7 dB and effective absorption bandwidth (EAB, with an RL of less than −10 dB) of 5.5 GHz at a thickness of 1.4 mm. Owing to the balance of the ameliorated impedance conditions and the synergetic effect of dielectric and magnetic loss, the microwave absorption performance was enhanced significantly.