Materials scientists at the Indian Institute of Technology in Roorkee (IIT-R) have developed microwave absorbing nanocomposite coatings that could make aircraft almost invisible to radar.
The technology for building invisible, or stealth aircraft, is a closely guarded secret of developed countries and a handful of laboratories in India are doing research in this area.
Radars that emit pulses of microwave radiation identify flying aircraft by detecting the radiation reflected by the aircraft's metallic body.
The nanocomposite coatings developed by Rahul Sharma, RC Agarwala and Vijaya Agarwala at IIT-R absorb most of the incident radiation and reflect very little.
Sharma, who revealed his team's work at an international nanomaterials conference held recently at the Indian Institute of Science in Bangalore, believes their nano-product is a significant step in developing a technology to enable aircraft escape radar surveillance and protect its equipment from electronic "jamming".
Nanoparticles - so called because of their very small size - are known to exhibit unique physical and chemical properties. The IIT team found that crystals of "barium hexaferrite" with particle size of 10-15 nanometres have the ability to absorb microwaves. (Human hair, for comparison, is 100,000 nanometres thick).
They developed special processes for synthesising the nanopowder and formulating it as a coating.
Sharma said that the nanocomposite coating on the aluminium sheet absorbed 89 per cent of incident microwaves at 15 giga hertz - the frequency normally used by radars - reflecting only 11 per cent. A stealth aircraft should ideally absorb all the incident radiation and reflect nothing.