X-Band microwave characterization of carbon-based nanocomposite material, absorption capability comparison and RAS design simulation

This paper presents a microwave characterization of several carbon-based composite materials interesting the future aircraft/aerospace systems. They consist in epoxy resin reinforced with five different carbon species: micro-sized granular graphite, fullerenes, carbon nanofibers, single- and multi-walled carbon nanotubes. Main goal of this work is to show how carbon inclusions size and geometry are able to significantly modify the electromagnetic properties at microwave frequencies. Microwave characterization is performed in terms of microwave permittivity and intrinsic wave impedance evaluation; all the computations are based on microwave scattering parameters measured in the X-band (8.2/12.4 GHz) by waveguide method. A theoretical analysis of the microwave absorbing capability is then performed assuming that a multilayer of nanocomposite material was backed on a conductor plate (such a structure is typically called Radar Absorbing Material). The results obtained for the reflection coefficient indicate that nanoparticles give better absorption properties to the matrix than micro-sized ones: nanocomposite materials could thus be used successfully as microwave absorbers, not only for their absorption performances but also for their light weight.