Dielectric constant, magnetic permeability and microwave absorption studies of hot-pressed Ba-CoTi hexaferrite composites in X-band

The microwave absorption, complex permittivity and complex permeability studies of hot-pressed hexaferrite composites prepared with Ba(CoTi)(x)Fe12-2xO19 (x = 0.0, 0.2, 0.4, 0.8, and 1.0) were made in the frequency range from 8.0 to 12.4 GHz. The hexaferrite composites with x > 0.0 exhibit significant dispersion in the complex permittivity (epsilon(r)'-j epsilon(r)''). However the dispersion in complex permeability (mu(r)'-j mu(r)'') is not significant and is attributed to the shielding effect of polymer matrix over the ferrite crystallites. The reflection loss has been studied as function of frequency, composition and thickness of absorber. A comparison of reflection loss of hot-pressed ferrite composites with that of normal sintered ferrite composites was made and analyzed. A minimum reflection loss of - 24.0 dB is obtained at 9.9 GHz for 2.8 mm thick sample of BaCo0.4Ti0.4Fe11.2O19 hot-pressed hexaferrite composite.