"Stealth" Plasma Antennas 169
eldavojohn writes "There's a new antenna that consists of plasma and essentially vanishes when you turn it off. While it may seem to not have many uses in the commercial world, it is very important to military personnel who risk detection or for anybody wishing to avoid signal jamming."
Re:How does a disappearing antenna help? (Score:3, Informative)
Non Slashdotted Link (Score:5, Informative)
Not News (Score:3, Informative)
http://www.newscientist.com/article/mg16422141.000-now-you-see-it---.html [newscientist.com]
Re:How does a disappearing antenna help? (Score:5, Informative)
Re:How does a disappearing antenna help? (Score:3, Informative)
--The FNP
TFA (Score:4, Informative)
A new antenna made of plasma (a gas heated to the point that the electrons are ripped free of atoms and molecules) works just like conventional metal antennas, except that it vanishes when you turn it off.
That's important on the battlefield and in other applications where antennas need to be kept out of sight. In addition, unlike metal antennas, the electrical characteristics of a plasma antenna can be rapidly adjusted to counteract signal jamming attempts.
Plasma antennas behave much like solid metal antennas because electrons flow freely in the hot gas, just as they do in metal conductors. But plasmas only exist when the gasses they're made of are very hot. The moment the energy source heating a plasma antenna is shut off, the plasma turns back into a plain old (non conductive) gas. As far as radio signals and antenna detectors go, the antenna effectively disappears when the plasma cools down.
This prototype plasma antenna is stealthy, versatile, and jam-resistant. Credit: T. R. Anderson and I. Alexeff
The antenna design being presented at next week's APS Division of Plasma Physics meeting in Orlando consists of gas-filled tubes reminiscent of neon bulbs. The physicists presenting the design propose that an array of many small plasma elements could lead to a highly versatile antenna that could be reconfigured simply by turning on or off various elements.
- T. R. Anderson and I. Alexeff 2007 APS Division of Plasma Physics annual meeting November 12, 2007
Lots of problems with this article (Score:5, Informative)
The idea that this could lead to a reconfigurable antenna is a bit farfetched, as it would require that the driving bias electrodes be able to totally float at RF frequencies. Just like a neon sign, or a fluorescent light, you're going to have to keep a large voltage across these to get them to light, so it'll be tricky to use it as a receiving antenna in particular.
Take a look at another project, Talking Lights [talking-lights.com]. This uses conventional fluorescent lights (hey, a plasma!) with a modified ballast to transmit data at serial-link speeds.
The "jam-resistance" doesn't make any sense. If it can receive signals, it can receive signals, period. At the point of the antenna, the desired signal and the jamming signal have already been mixed. The antenna itself can't help you out. (Clever frequency-hopping or other schemes can, though.)
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Microcontroller kits for the digital generation. [nerdkits.com]
I remember these things..... (Score:5, Informative)
Re:How does a disappearing antenna help? (Score:5, Informative)
Re:Hides by Glowing in the Dark? (Score:2, Informative)
it can be synthed without too much trouble, but the cost of an alum.ox. antenna would still probably be pretty high, though. while it's cheaper to create a gem in the lab than buy a wild one, that's just for gem-sized pieces. it'll cost a fair shake regardless if you're talking about FEET (or METERS) rather than inches or mm.