Dielectric constant, permeability and microwave absorption studies of Ba-NiTi hexaferrite composites in X-band

The effect of Ni2+Ti4+ substitution on complex permeability and permittivit y and microwave absorption has been studied for Ba(NiTi)(x)Fe(12-2x)0(19) h exaferrite-epoxy composites, wherein x varies from 0.0 to 1.0 in steps of 0 .2, in the frequency range 8.0-12.4 GHz. The hexaferrite-composites with x < 0.6 exhibit significant dispersion in the complex permittivity (epsilon'- j epsilon ") with maximum value of epsilon " is observed for x equal to 0.6 . The dispersion in the complex permeability (mu'-j mu ") is not significan t which is attributed to the reduced interaction between crystallises of fe rrites and low alternating electromagnetic field applied to the sample. The variation of reflection loss has been studied as a function of frequency ( f), Ni2+Ti4+ Content (x) and thickness of the absorber (d). A minimum refle ction loss of -30.0 dB is obtained for composites with x equal to 0.6 and a bsorber thickness of 2.75 mm. The experimental values of the matching frequ ency and the matching thickness agree well with the theoretical values obta ined by solving the equations numerically.