Dielectric property of unidirectional triangle-shape carbon fiber reinforced polymeric composites

Triangle-shape carbon fiber reinforced polymeric composites is a plausible material for fabricating the radar absorbing structure. In order to design the effective electromagnetic wave absorber, the dielectric properties of its constituents are required in the target frequency band. In this paper, the unidirectional triangle-shape carbon fiber/epoxy composites were manufactured and the carbon fiber volume fraction of composite materials was measured to be about 46%. And then the permittivities of specimens were tested with the rectangle waveguide method in the vertical direction and in the parallel direction. The theoretical models and prediction equations for estimating permittivity of the unidirectional triangle-shape carbon fiber/epoxy composites were proposed with respect to the fiber volume fractions, the cross-section shape of fiber, the fiber orientations and the permittivity of components. It was found that the theoretical values agreed well with the experimental results.