Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite

Carbonyl iron and barium ferrite powder (BaZn_1.5Co_0.5Fe₁₆O₂₇) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2-18 GHz was created. Based on the database, the single-layer and double-layer absorbers were designed and prepared, and their microwave absorption properties were investigated. The results indicate that the carbonyl iron powder prepared via thermal decomposition of iron pentacarbonyl is single cubic iron and of spherical shape. The barium ferrite powder is single W-type ferrite and a hexagonal flake. The absorption band of the double-layer microwave absorber is obviously more than that of the single-layer absorber. The double-layer microwave absorbers with reflection loss <-13 dB over the range of 6-18 GHz and reflection loss <-8 dB over the range of 2-18 GHz were prepared. The thicknesses of the absorbers are only 3.6 and 3.7 mm, respectively.