Wide-band electromagnetic wave absorber of rubber-ferrite

Two different compositions with Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 2.1/Fe/sub 9.9/ O/sub 19/ and Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 3.2/Fe/sub 8.8/O/sub 19/ of barium ferrite with a magnetoplumbite structure (M-type) had been obtained by conventional ceramic technology. The complex permeability and permittivity of the materials were measured in the 2-18 GHz band. Ba M-type ferrite materials mixed with polyvinyl chloride, plasticizer and frit are pressed to form flakes (180 mm/spl times/180 mm/spl times/2 mm) of rubber-ferrite. The absorption properties of the single layer rubber-ferrite absorber are measured by an Agilent 8722ES network analyzer (2-18 GHz). Compared with the theoretical calculation, it was found that preferable properties of microwave absorption were obtained by using a bank of two ferrite materials singly over a narrow frequency region. Almost all of the samples in the multi-layer rubber-ferrite absorber exhibited a minimum reflection loss less than -10 dB with a thickness (d/sub m/) 22 mm.