Electromagnetic Characteristics of Carbon Nanotube Based Antennas

Abstract

We have studied electromagnetic characteristics of carbon nanotube based antennas in different frequency regimes ranging from the microwave to visible. Analysis of the physical characteristics of carbon nanotube based integrated circuit elements, such as antennas, must follow the general principles of electrodynamics and must account for the peculiar dispersion properties of electrons in carbon nanotubes. A key element of the analysis is the formulation of the effective boundary conditions for electromagnetic field on the carbon nanotube surface. We have incorporated the presence of intershell tunneling in the effective boundary conditions, showing thereby that tunneling alters the effective boundary conditions significantly from the effective boundary conditions presented previously. In order to incorporate intershell tunneling in the effective boundary conditions, we have adopted a microscopic approach. We observed that intershell tunneling qualitatively changed the form of effective boundary conditions in a doublewall carbon nanotube in comparison to single wall carbon nanotubes. The surface current densities and the axial component of the electric field on the surfaces of different shells get coupled, which effect leaded to a generalized susceptibility that contained the mutual surface conductivities of both shells. The mutual surface condivities are caused by the tunneling. The existence of mutual condivities leaded to the appearance of electrostatic longitudinal waves in the spectra of a double wall carbon nanotube. Different types of guided waves in the double wall carbon nanotube arise from intershell tunneling. The dispersion characteristics of asymmetric like waves are strongly affected in the wide frequency range by intershell tunneling.