Broadband absorbers of electromagnetic radiation based on aerogel

Abstract

An inhomogeneous broadband absorber of electromagnetic energy constructed from an aerogel-lossy dielectric composite, where the concentration of the lossy dielectric increase across its thickness such that the composite's dielectric properties vary from those of the aerogel to those of the lossy dielectric. Materials useful for serving as the lossy dielectric include polar molecules, polar icosahedral molecules, polyaniline electron-conducting polymers, and polyprrole electron-conducting polymers. Another inhomogeneous layer absorber is constructed from an aerogel that is intrinsically a lossy dielectric. The variation in dielectric properties is achieved by increasing the density of the aerogel across the thickness of the material. Aerogel materials for such an absorber include organic aerogels which have been pyrolized in an inert atmosphere to give vitreous carbon aerogels. Methods for fabricating these absorbers are described.