Three-Layer Structure Microwave Absorbers Based on Nanocrystalline α-Fe, Fe_(0.2)(Co_(0.2)Ni_(0.8))_(0.8) and Ni_(0.5)Zn_(0.5)Fe_2O_4 Porous Microfibers

摘要

The three-layer structure microwave absorbers with thickness of 2 mm were designed based on nanocrystalline α-Fe, Fe_(0.2)(Co_(0.2)Ni_(0.8))_(0.8) and Ni_(0.5)Zn_(0.5)Fe_2O_4 porous microfibers with diameters about 2-5 μm. The electromagnetic parameters and microwave absorption properties were investigated by vector network analyzer in the frequency range of 2-18 GHz. The results show that the three-layer structure microwave absorbers display stronger absorption properties in a wide frequency range than the single-layer and double-layer microwave absorber. For the three-layer structure, the microwave absorption properties are mainly influenced by the microfibers layer arrangement order, total thickness and each layer thickness. When the Ni_(0.5)Zn_(0.5)Fe_2O_4 porous microfibers layer is arranged as the impedance-matching surface layer, with a total thickness of 2 mm consisting of 0.7 mm thick α-Fe porous microfibers inner layer, 0.9 mm thick Fe_(0.2)(Co_(0.2)Ni_(0.8))_(0.8) porous microfibers medium layer and 0.4 mm thick impedance-matching surface layer, the three-layer structure has a strongest microwave absorption of 45.7 dB at 12.8 GHz, the absorption bandwidth (with RL < -10 dB) of 10.2 GHz from 7.8 GHz to 18 GHz and bandwidth (with RL < -20 dB) of 4.4 GHz from 11.1 GHz to 15.5 GHz respectively. This three-layer structure is promising microwave absorbers to meet the requirements of thin thickness, light weight and wide band for military and civil applications.