The ceramics of PbTiO 3 and its powders have been prepared by a sol-gel process. The constitution of its phase and structure was examined by x-ray diffraction and Fourier transform infrared spectroscopy. Characterization studies were performed to determine the effects of particle size and degree of tetragonality. The dielectric properties of ceramics and powders of PbTiO 3 , composited with paraffin, were measured from 1 MHz to 18 GHz. All samples exhibited evidence of relaxation phenomena in their dielectric spectra. The relaxation frequencies increased with decreasing particle size.

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Based on Maxwell equations, the theoretical formulas of microwave electromagnetic parameters of polycrystalline iron fiber absorber are dervied. The anisotropy of microwave electromagnetic parameters of polycrystalline iron fiber absorber is explained by use of numerical calculations. Some samples of fiber orientation have been produced and their electromagnetic parameters have been tested, the results confirm the anisotropy of electromagnetic parameters. Both of the theoretical and experimental results demonstrate that the axial permeability of polycrystalline iron fiber is greater than its radial permeability, and the axial permittivity of polycrystalline iron filber is greater than its radial permittivity.

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