[ExI] Fw: UFO UpDate: Cloaking Throws An Electromagnetic Curveball

Terry Colvin fortean1 at mindspring.com
Fri Jan 16 09:08:46 UTC 2009

-----Forwarded Message-----
>Source: ars technica.com - New York, New York, USA
> http://tinyurl.com/a6ufcv
>January 15, 2009
>New Cloaking Surface Throws An Electromagnetic Curveball
>By Tim De Chant
>For centuries, humans have dreamed of fading into the 
>background. Hunters have long wished to vanish into their 
>surroundings, and these days, awkward moments at parties can 
>evoke similar desires. But the ability to truly disappear is 
>still only found in tales spun by writers and filmmakers, as 
>cloaking has remained the stuff of fantasy and science fiction. 
>Thanks to some pioneering researchers, however, cloaking has 
>moved one step closer to reality.
>Six scientists have built a sophisticated metamaterial that 
>literally bends electromagnetic waves, according to a new paper 
>published Thursday in the journal Science. Ruopeng Liu and 
>Chunlin Li, researchers in David R. Smith's lab at Duke 
>University, along with three other colleagues, assembled more 
>than 10,000 specially designed pieces to form a mat 20 inches 
>long and four inches wide. When finished, the yellow pad sucked 
>microwaves in and spit them out-with a curve.
>To test their new invention, researchers first beamed microwaves 
>at a flat, mirrored surface. The waves behaved as they should, 
>bouncing off at a predictable angle. Next they shot it at a bump 
>in a mirrored surface. The microwaves bounced and scattered, 
>carefully obeying the laws of physics. Then the scientists laid 
>their yellow mat over the bump. And the wave ignored the bump-or 
>so it seemed. After reflecting off the curved surface, the 
>radiation veered downward and continued along a flat surface-
>trajectory. The mat had cloaked the bump.
>Aside from starring in the Harry Potter series and countless 
>Star Trek incarnations, cloaking has been a very serious and 
>very active research area in the past few years. In May 2006, 
>two scientists proposed active cloaking devices based on 
>superlenses, but their contribution at the time was only 
>theoretical. The reality of superlenses hasn't been as 
>promising, but in October of that same year, Smith and his 
>colleagues presented a cloaking breakthrough-the ability to 
>cloak an object from a specific microwave frequency. More papers 
>followed, and the science progressed rapidly. But then last 
>December, a new theoretical study published gave researchers a 
>harsh reality check-cloaking at multiple frequencies may very 
>well be impossible, the authors said. As the number of cloaked 
>frequencies increases, the efficacy of the device or material 
>decreases. It's a classic tradeoff, they implied, and one not 
>likely to be overcome.
>Liu and Li's new research, though, seems to poke a giant hole in 
>that last paper. Their new metamaterial masks not one tiny slice 
>of the microwave spectrum, but a relatively large swath of it, 
>from 13 to 16 gigahertz. Liu and Li built off the results of 
>Smith's 2006 paper to create the new cloak, but this time used 
>more powerful algorithm to help them fabricate the metamaterial. 
>The formula dictated where each of the over 10,000 pieces in the 
>structure should be placed to achieve the desired effect.
>"The difference between the original device and the latest model 
>is like night and day," Smith said in a press release. While the 
>earlier, more limited device took Smith and his team four months 
>to build, the new, more capable cloak was ready in only nine 
>Smith compares the mat's cloaking effect to a mirage. "You see 
>what looks like water hovering over the road, but it is in 
>reality a reflection from the sky," he said. "The mirage you see 
>is cloaking the road below."
>While you won't be able to don a fancy blanket and duck out of 
>work early any time soon, the new metamaterial proves that one 
>surface can cloak many frequencies. Three gigahertz is certainly 
>a far cry from the 350,000 GHz that make up the visible 
>spectrum, but at least it's a step in the right direction. 
>Science, 2008. DOI: http://dx.doi.org/10.1126/science.1166949
>[Thanks to Frank Fields for the lead]

Terry W. Colvin
Ladphrao (Bangkok), Thailand
Pran Buri (Hua Hin), Thailand

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