Double-layer microwave absorber based on nanocrystalline Zn0.5Ni0.5Fe2O4/α-Fe microfibers

Abstract

The microwave absorption properties of the nanocrystalline NiZn ferrite (Zn0.5Ni0.5Fe2O4) and iron (α-Fe) microfibers with single-layer and double-layer structures were investigated in the frequency range of 2–18GHz. The double-layer absorbers have much better microwave absorption properties than the single-layer absorbers, and the microwave absorption properties of the double-layer structure are influenced by the coupling interactions between the absorbing layer and matching layer. With the absorbing layer thickness 0.7mm of α-Fe microfibers–wax composite and the matching layer thickness 1.5mm of Zn0.5Ni0.5Fe2O4 microfibers–wax composite, the minimum reflection loss (RL) reaches about −71dB at 16.2GHz and the absorption band width is about 9.2GHz ranging from 8.8 to 18GHz with the RL value exceeding −10dB. While, when the absorbing layer is the Zn0.5Ni0.5Fe2O4 microfibers–wax composite with thickness 1.8mm and the matching layer is the α-Fe microfibers–wax composite with thickness 0.2mm, the RL value achieves the minimum about −73dB at 13.8GHz and the absorption band width is about 10.2GHz ranging from 7.8 to 18GHz with the RL value exceeding −10dB, which covers the whole X-band (8.2–12.4GHz) and Ku-band (12.4–18GHz).