Microwave absorbing properties of composites filled with glass-coated Fe69Co10Si8B13 amorphous microwire

The electromagnetic parameters and microwave absorbing properties of paraffin and polymer composites filled with glass-coated Fe69Co10Si8B13 amorphous microwire (GCFAW) were investigated. The results show that the microwire filling ratio and annealing temperature have no obvious influence on the complex permeability, while they exhibit significant effect on the complex permittivity. The complex permittivity increases remarkably with the increase of microwire filling ratio, and decreases sharply with increasing the annealing temperature. With the increase of microwire filling ratio and absorber thickness, the minimum reflection loss decreases firstly and then increases, and shifts towards lower frequency region. For the paraffin composite with GCFAW filling ratio of 15% and thickness of 1.4 mm, the minimum reflection loss is −28.5 dB and the frequency bandwidth less than −10 dB is 2.9 GHz. When the microwire filling ratio and the thickness of paraffin composite are invariant, the frequency of minimum reflection loss shifts towards higher region with increasing the annealing temperature. The change trend of measured reflection loss of polymer composite is consistent with that of calculation reflection loss of paraffin composite, but the minimum reflection loss increases a little and shifts towards lower frequency. As the microwire filling ratio is 15%, the reflection loss of polymer composite exhibits two extreme values.