It would be great if you provide some more information on subject... though triangular-shaped crystals have been used before as Radar absorbent beneath the exterior, bouncing the signal around until death.
This on is from BR site but the link mention in the site is not working
IIT Roorkee develops coating that can make aircraft invisible
The Indian Institute of Technology, Roorkee, has claimed that it has developed a kind of coating material in their laboratory that can make aircraft invisible to any radar. It said the technology on which it worked to develop the radar absorbing nano-crystals was their brainchild and after NASA, India was only one to have successfully gained the technology.
"Even a country like Russia could not achieve this so far," said Prof R.C. Agarwala of Metallurgical and Materials Engineering, who led the project. Prof Agarwala, who is known to be the first in the country to work on nanotechnology for materials development, started work on the radar-absorbing nano crystals in 1998.
His research team included his wife Prof Vijay Agarwala who is also a faculty of the department and research scholar Rahul Sharma.
AND this is form the link provided by "godsavetheworld"
IIT develops technology to produce stealth aircraft
By IANS
Tuesday,07 November 2006, 00:00 hrs
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Bangalore: 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, R.C. 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 here, 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 synthesizing the nanopowder and formulating it as a coating.
Sharma said that the
nanocomposite coating on the aluminium sheet absorbed 89 percent of incident microwaves at 15 giga hertz - the frequency normally used by radars -- reflecting only 11 percent. A stealth aircraft should ideally absorb all the incident radiation and reflect nothing.
