From blackness to invisibility - Carbon nanotubes role in the attenuation of and shielding from radio waves for stealth technology

Stealth technology combines numerous means and techniques to be 'invisible' for opponents in a battle field. Since metals are the key construction materials of military vehicles, weapon and equipment, they can be targeted and detected by RAdio Detection And Ranging (RADAR) systems. Radar-Absorbent Materials (RAMs) - as crucial components of passive countermeasures in the modern-day military tactics - are used for absorption of electromagnetic waves. In the same time, mainly due to high electric conductivity, RAMs - accompanied by designed geometry of the objects they are incorporated into - can yield programmable reflection, multiple internal reflection and scattering towards Electromagnetic Interference (EMI) shielding. Nowadays, the latest achievements of nanotechnology have transformed stealth technology into an even more powerful tool. And among many nanomaterials, carbon nanotubes (CNTs) have arisen as one of the most promising active component of RAMs and EMI shielding materials. The unique sp2-derived macromolecular architecture equips CNTs with an exceptional combination of electromagnetic, mechanical and chemical properties. This review intends to summarize and critically evaluate the hitherto efforts in the production and applications of CNT nanocomposites/hybrid materials as key constructional civil and military elements, preferably as coatings, layers, films, textiles or panels, towards attenuation of the radio wave radiation.

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