An ultra-broadband electromagnetically indefinite medium formed by aligned carbon nanotubes (original) (raw)

2011

Anisotropic materials with different signs of components of the permittivity tensor are called indefinite materials. Known realizations of indefinite media suffer of high absorption losses. We show that periodic arrays of parallel carbon nanotubes (CNTs) can behave as a low-loss indefinite medium in the infrared range. We show that a finite-thickness slab of CNTs supports the propagation of backward waves with small attenuation in an ultra-broad frequency band. In prospective, CNT arrays can be used for subwavelength focusing and detection, enhancing the radiation efficiency of small sources.

Carbon nanotube based structure with high absorption in X-band

2013 International Symposium on Electromagnetic Compatibility, 2013

Multi-layer structures of single-walled carbon nanotubes mixtures with epoxy resin at different weight percentages are studied for maximizing the absorption of incident waves over X-Band. A short survey is also performed in 1-5 GHz. A plane wave from various elevation angles is illuminating the structure. Comparison with reference results shows satisfactory agreement. An optimization method is adopted for minimizing both the Reflection and Transmission Coefficient with respect to the optimum thickness of each layer for structures with and without perfect electric conducting substrates. A drastically increased absorption greater than 90% is achieved with the presence of carbon nanotubes even without the use of perfect electric conducting substrates. Total thickness is similar to structures with perfect electric conducting substrates promising thus innovative and interesting components for both electromagnetic compatibility and radar absorbing material applications.

Carbon Nanotubes as Optical Antennae

Advanced Materials, 2007

AbstractCompelling evidence of the antenna action of multiwall carbon nanotubes arranged in a random array is provided by demonstrating that the directional radiation characteristics are in good agreement with conventional radio antenna theory and simulations. Basic antenna effects are investigated: the polarization and the antenna length effect. The figure shows the measured radiation pattern from an array of multiwalled carbon nanotubes.

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