Patent ID: 7794629
Filing Date: 2010-09-14
Classification: H01B,Y10T

Abstract:
1. A composite material comprising a proportion of an electrically non-conductive material and a proportion of a randomly distributed electrically conductive material, and wherein: a) the electrically non-conductive and conductive materials are both particulate; b) the electrically non-conductive material is a polymer; c) the electrically conductive material is a metal, metal alloy, conductive metal oxide, a conductive ceramic material or a mixture of two or more of these; d) the electrically non-conductive material has an average particle size which is at least ten times that of the electrically conductive material and defines an excluded volume microstructure for the composite material, the excluded volume microstructure comprising regions which exclude the electrically conductive material and other regions which contain the electrically conductive material; e) the electrically conductive material is sufficiently well dispersed in the composite material and its proportion is appropriate to establish at least one electrically conducting network as a coating over the surfaces of particles of the electrically non-conductive material, the network providing for the composite material to be electrically conducting and to exhibit a plasma-like response and a plasma frequency which is below conventional bulk metals' plasma frequencies, the plasma frequency being associated with a change in the composite material's real permittivity from positive to negative; f) the composite material has a conductivity greater than 10 S/m; and g) the composite material is incorporated in a product, device or apparatus selected from the group consisting of products, devices and apparatuses for modifying the propagation characteristics of electromagnetic radiation incident upon it, a lens, a filter, a transparent electrode, an absorbing electrode, a capacitor, an inductor, a waveguide, a sensor, a remote interrogation sensor package, an active electromagnetic shutter, a radome, a switch, a shield, fuse, an anechoic chamber or combinations thereof.