Published online by Cambridge University Press: 21 February 2011
Composites of metal filled particulates, Al, Cu, Si(doped), Ag and Ni, up to 45 volume percent in a polyester or epoxy matrix were made and their dielectric properties measured between 8.5 and 11.5 GHz. The particulate size was small relative to the wavelength of the microwave radiation, but in general large compared to the skin depth. For all systems the real part of the dielectric constant increases rapidly with volume fraction filler. Some correlation was also found between the dielectric constant and the average aspect ratio of the particulates, based on the number of particulates in contact. In addition particle type and size was important. The imaginary part of the dielectric constant was small except for samples that appeared to be on the verge of percolation.