Anisotropic microwave absorbing properties of oriented SiC short fiber sheets

SiC fibers are a kind of anisotropic microwave absorbing materials due to their fiber-shaped semi-conductive properties. In this paper, oriented SiC short fiber sheets were prepared and their anisotropic electromagnetic parameters and microwave absorbing properties were measured and analyzed. It is found that axial permittivity of SiC fibers was several times larger than their radial permittivity. With increasing volume content, both real part and imaginary part of permittivity increased obviously. Simulated microwave absorbing properties based on measured anisotropic electromagnetic parameters coincide well with those measured results. Both the orientation angle and the number of layers, as well as the fiber direction of the top layer, affect the anisotropic property greatly. The higher the orientation angle and the number of layers, the more isotropic microwave absorbing properties the multilayer sheets have. (c) 2009 Elsevier Ltd. All rights reserved.