Wideband microwave absorption in thin nanocomposite films induced by a concentration gradient of mixed carbonaceous nanostructures

Absorption in excess of 90% is induced over a 22 GHz bandwidth by the combination of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) dispersed in a polymer matrix. This performance is achieved by a stack of polymer films showing a concentration gradient of mixed CNTs and GNPs from layer to layer, having a total thickness of only 0.76 lambda/4.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.76\,\lambda /4.$$\end{document} Excellent agreement is observed from 18 to 40 GHz between the predicted and measured reflectivity and the resulting high absorption.