Radar absorbing properties of carbon nanotubes/polymer composites in the V-band

Abstract

This research is devoted to the study of radar absorbing properties of the composites, based on the epoxy binder and carbon nanotubes (CNT) in the frequency range of 52-73 GHz. Three species of unmodified multi-walled CNT differing in length and diameter were investigated as fillers. The reflection coefficients (Krefl) at the radar absorbing material (RAM)-air interface and the electro-magnetic radiation (EMR) absorption coefficients (Kabs) in the materials with the different content of nanotubes were measured (Krefl and Kabs were calculated using the highest (the worst) value of the voltage standing-wave ratio (VSWR) in the frequency range of 52-73 GHz). It was established that the increase in nanotubes aspect ratio (a ratio of CNT length to its diameter) leads to Kabs rising for polymer composites. Also, CNT diameter decrease leads to Krefl reduction. CNT of 8-15 nm in diameter and more than 2 ìm in length are the most effective from all investigated fillers. The reflection loss values were calculated and CNT optimal concentrations were obtained at different thickness of RAMs.