Double-layer microwave absorber based on ferrite and short carbon fiber composites

Sol-gel method was used to prepare M-type BaFe12O19 and W-type BaCo2Fe16O27 hexaferrites. Electromagnetic parameters of the ferrites composites and M-type ferrite composite filled with short carbon fiber were measured at Ku waveband, and their reflectivity was calculated according to transmission-line theory, respectively. Based on the above calculation, double-layer absorbers of thickness d = 2 min containing W-type ferrite composite and M-type ferrite composite filled with short carbon fiber were designed, and their microwave absorption properties were predicted. The results of prediction show that the absorber whose inner layer is W-type ferrite composite and thickness of each layer is 1 min has excellent microwave absorption properties. The bandwidth less than -10 dB of the double-layer composite reached 3.2 GHz, and peak value is - 22.0 dB at about 12.7 GHz. (c) 2007 Elsevier B.V. All rights reserved.