Double-layer microwave absorber of nanocrystalline strontium ferrite and iron microfibers

Abstract

Microwave absorption properties of the nanocrystalline strontium ferrite (SrFe12O19) and iron (α-Fe) microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz–18 GHz. For the single-layer absorbers, the nanocrystalline SrFe12O19 microfibers show some microwave absorptions at 6 GHz–18 GHz, with a minimum reflection loss (RL) value of −11.9 dB at 14.1 GHz for a specimen thickness of 3.0 mm, while for the nanocrystalline α-Fe microfibers, their absorptions largely take place at 15 GHz–18 GHz with the RL value exceeding −10 dB, with a minimum RL value of about −24 dB at 17.5 GHz for a specimen thickness of 0.7 mm. For the double-layer absorber with an absorbing layer of α-Fe microfibers with a thickness of 0.7 mm and matching layer of SrFe12O19 microfibers with a thickness of 1.3 mm, the minimum RL value is about −63 dB at 16.4 GHz and the absorption band width is about 6.7 GHz ranging from 11.3 GHz to 18 GHz with the RL value exceeding −10 dB which covers the whole Ku-band (12.4 GHz–18 GHz) and 27% of X-band (8.2 GHz–12.4 GHz).