Microwave absorption capability of microcapsules by coating FeSiAlCr with SiO2

Electromagnetic wave absorption of microcapsules by coating FeSiAlCr with SiO2 is investigated. The absorption amplitude of the microcapsules is found to increase significantly in the lower frequency of microwave compared with the corpuscles of FeSiAlCr alloy. Reflection loss (RL) exceeding −10 dB can be obtained for all frequencies within 2.6–7.3 GHz, covering half of the S-band, and the whole C-band when the absorber layer thickness is 2 mm. The maximum RL can exceed −18 dB at 4.3 GHz, while the RL is only −4 dB with the corpuscles of FeSiAlCr alloy. The reason is that the microcapsules's conductance is decreased and the absorption of electromagnetic wave in the microcapsule materials is easier.