ARLA/CLUSTER: Tornar invisiveis torres, mastros e antenas.

[João Gonçalves Costa]

Ham-genuity makes Invisibility Cloak real

In 2008, Chip Cohen, W1YW invented the first wideband invisibility cloak, using it to slip stream microwaves from one side of an object to another. But Harry Potter, aside, where is the 'killer app'?

W1YW found that killer app-making towers, mast, and coax disappear. With a new version of the patent and patent pending invisibility cloak,showcasing 3D, he made an antenna mast section disappear, with a wide bandwidth, at UHF and microwave. The RF waves curled around the mast to the opposite side, as if the mast wasn't there. "The moment was chilling. Suddenly invisibility cloaks became far more than playthings for egghead scientists chasing grants. They are practical devices. "

Practical means far reaching, from taking nearby antenna elements selectively out of an antenna pattern to hiding a rocket from radar. And with new techniques in x ray etching, the prospect for a visible light invisibility cloak "seems certain", notes Cohen.
Cohen cites his ham radio experience as a continual source of knowledge and technique. "Although I am a professional scientist and retired college professor, it's really ham radio that affords permission to tinker, even now."

The invisibility cloak is a layered structure made from little fractal resonators, arranged close together, much like Marconi and Franklins' 1919 antenna reflector made from conventional end loaded resonators. But this arrangement guides waves around an object so they appear on the opposite side. "There is no power and no little guy inside flicking some switch. " The 3D invisibility cloak can be seen here:
http://www.youtube.com/embed/2BrVxpPYMiA?rel=0

The first demonstration of the 3D invisibility cloak was shown to visitors of the Radio Club of America on June 9. Speaking at the Boxboro (New England) Ham Convention in August, W1YW will again be demonstrating the invisibility cloak for the convention audience.

Press release

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