Title :
Electromagnetic Simulation and Measurement of Carbon Nanotube Thread Dipole Antennas
Author :
Keller, Steven D. ; Zaghloul, Amir I. ; Shanov, Vesselin ; Schulz, Mark J. ; Mast, David B. ; Alvarez, Noe T.
Author_Institution :
U.S. Army Res. Lab., Adelphi, MD, USA
Abstract :
The conductivity, current distribution, and radiation efficiency for a variety of dipole antennas constructed from carbon nanotube thread/rope are simulated using Hallén´s integral equation for a thin wire applied to the method of moments and are compared to a standard copper wire dipole antenna. Next, the conductivity and weight of fully fabricated carbon nanotube thread and rope samples are measured and analyzed. Finally, half-wavelength copper and carbon nanotube (CNT) thread dipole antenna prototypes are fabricated, measured, and analyzed. Simulation results indicate that the CNT thread/rope antenna performance improves with increased diameter and that the application of these materials as a half wavelength dipole antenna yields manageable losses of less than 1-5 dB at RF frequencies above 10 GHz. Measured sample results demonstrate that the existing single-ply CNT thread exhibits a conductivity approximately 2-3 orders of magnitude lower than copper. The braiding method employed to produce large diameter CNT rope was demonstrated to be a poor method for increasing thread diameter and conductivity due to the additional resistive losses that the braiding geometry introduced. Dimethyl sulfoxide densification was found to be a valuable method for improving CNT thread conductivity and lowering the thread contact resistance. Dipole antenna prototype measurements confirm the functionality of the CNT thread as an antenna, albeit with a 4% downward frequency shift due to reactance effects and material losses of greater than 12 dB at 2.45 GHz as predicted by the results from the method of moments simulations.
Keywords :
carbon nanotubes; current distribution; dipole antennas; integral equations; method of moments; wire antennas; CNT thread conductivity; Hallén integral equation; braiding geometry method; carbon nanotube thread dipole antennas; current distribution; dimethyl sulfoxide densification; dipole antenna conductivity; electromagnetic measurement; electromagnetic simulation; half-wavelength copper; method of moment simulations; radiation efficiency; resistive losses; rope antenna performance; rope samples; standard copper wire dipole antenna; thin wire; Antenna measurements; Conductivity; Copper; Dipole antennas; Wires; Yarn; Carbon nanotube (CNT); Hallen’s integral equation; dimethyl sufoxide; dipole antenna; method of moments;
Journal_Title :
Nanotechnology, IEEE Transactions on
DOI :
10.1109/TNANO.2014.2306330