Anisotropic Microwave Properties of Vertically Aligned Carbon Nanotube Arrays

This article reports the complex electromagnetic (EM) permittivity and permeability of vertically aligned carbon nanotube (VACNT) arrays. Free-standing VACNTs were synthesized using thermal chemical vapor deposition (CVD) and measured with a vector network analyzer to measure the scattering parameters (S-parameters) of the material in the microwave frequency range of 8-18 GHz. The anisotropic complex permittivity and permeability of the VACNT arrays were calculated by converting the S-parameter measurements using the Nicolson-Ross-Weir method. VACNT arrays were found to be partially anisotropic, displaying varying degrees of lossy dielectric, and diamagnetic behavior. This method proves the viability of empirically modeling the EM properties of VACNT arrays within the frequency range of interest. The overarching EM behavior of VACNT arrays will be a key contribution to the design of carbon nanotube (CNT) applications in high-frequency electronics of the future.