Microwave absorption properties of double-layer absorber based on carbonyl iron/barium hexaferrite composites

The microwave absorption properties of BaCo_0.4Zn_1.6Fe₁₆O₂₇ ferrite and carbonyl iron powder with single-layer and double-layer composite absorbers were investigated based on the electromagnetic transmission line theory in the frequency range from 1 to 14 GHz. XRD was used to characterize the structure of prepared absorbing particles. SEM was used to examine the micromorphology of the particles and composites. The complex permittivity and permeability of composites were measured by using a vector network analyzer. The reflection loss of the single-layer and double-layer absorbers with different thicknesses and orders was investigated. The results show that double-layer absorbers have better microwave absorption properties than single-layer absorbers. The microwave absorption properties of the double-layer structure are influenced by the coupling interactions between the matching and absorption layers. As the pure ferrite used as matching layer and the composite of BF-5CI used as absorption, the minimum RL of absorber can achieve to −55.4 dB and the bandwidth of RL <−10 dB ranged from 5.6 to 10.8 GHz when the thicknesses of matching layer and absorption layer were 0.9 and 1.4 mm, respectively.