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"Stealth" Plasma Antennas
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."
How does having the antenna "disappear" effect it's ability to circumvent jamming? The article is apparently being slashdotted as I type this, so I'm just curious.
I got a catholic block.
When I submitted this story, I submitted the story from PhysOrg and I'm not sure why they changed the link. That poor blog didn't stand a chance. I guess they must do that to more randomly distribute their news sources or make it look like they aren't playing host to some PhysOrg worker trying to generate more traffic. Oh well, enjoy a usable link anyhow.
My work here is dung.
If it helps with signal jamming, I want it integrated into my cell phone! What do you mean it doesn't have commercial viability?
--The FNP
I read this in new scientist years ago:
http://www.newscientist.com/article/mg16422141.000-now-you-see-it---.html
(Sorry ham radio nerd humor.)
Disguise it as a stealth-plasma flagpole and proudly fly a red-white-and-blue flaming sheet-o-plasma flag! Has the added advantage of shocking the hell out of any pot-smoking hippies who try to burn it!
Give a man a fish and you have fed him for today. Teach a man to fish, and he'll say "WHERE'S MY FISH, YOU IDIOT?"
'Stealth' Antenna Made Of Gas, Impervious To Jamming Submitted by News Account on 12 November 2007 - 2:58pm. Physics
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
Letter To Iran
In a normal antenna, electrons in the metal slosh up and down, accelerated by the electromagnetic fields that it's receiving (or transmitting). In this case, I could use the same description: electrons slosh up and down, driven by the EM fields.
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. 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.)
--
Microcontroller kits for the digital generation.
OK, so you don't have a big metal antenna...Instead, you have a big structure built out of evacuated glass tubes resembling Neon tubes.
/frank
And you're going to take this out on the battlefield?
Now, the concept of changing the resonant frequency of the antenna by activating different individual elements is kinda cool, but this doesn't look stealthy at all.
And the worms ate into his brain.
Back in my university days I had the pleasure of being taught by a physicist turned engineer who was actually working on one of these things. The trouble with traditional antennas is their giant radar footprint and traditionally they solved this problem by flopping the antennas up and down when they needed to send signals. Not the most graceful solution so they started looking for alternatives. We had one of the prototypes of these things in the plasma instrumentation lab and it was pretty adept at sending some small signals. The great thing about them is their tunability. Just like any kind of woodwind instrument if you change the length of the tube (imagine a giant piston that's got plasma in it) you change the resonant frequency. My lecturer referred to it as playing the plasma trombone. Good to see these things finally making their way through to practical uses. I was always hoping my crazy lecturer's tinkerings would be used someday.
The Refined Geek - Technology, Finance, Space and everything in between
The original link works for me
'Stealth' Antenna Made Of Gas, Impervious To Jamming
Submitted by News Account on 12 November 2007 - 2:58pm.
Physics
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.
Picture:
http://www.scientificblogging.com/files/plasma%20antenna.jpg
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
So uhh.. how does this prevent jamming?
Because you have a broader range of frequencies to hop?
[Fuck Beta]
o0t!
The pic from TFA looks a bit dainty for combat use. I think a whip antenna is probably still more reliable and has a smaller radar signature for short range communication (IE a couple dozen miles). And the big ones, well, there's no hiding them.
Plus that whole bright and hot thing tends to attract the attention of certain guided missiles and sensor systems...not good! Maybe if they paint the glass or something...at least the light problem is solved.
I reposted the article just above. The picture shows a glowing u-shaped florecent tube. By "disappear" I believe they just mean large radar return. Such materials are called PECs in radar parlance (Perfect Electrical Conductor). You will still be able to see the tube visually.
In related speculation, I wonder if you could use the ION beam from a space probe's thruster (assuming Ion Drive of course) as an antenna. Of course since it wouldn't be parabolic or very directional it might be of limited use.
Letter To Iran
Rosie O'Donnell much?
Do you even lift?
These aren't the 'roids you're looking for.
Everyone should go out an buy a new plasma antenna before they switch on Feb 17, 2009. After that, your old metal ones will have to have an adapter to work.
Yup totally undetectable, its not like the enemy has the equipment to spot the infrared thrown of by gas heated to super high energy levers or anything. So much harder to see then a metal pole.
Repeal the 17th Amendment TODAY! Also Please Read http://www.gnu.org/philosophy/right-to-read.html
If it needs glass tubes to work, its not like it will just 'dissapear', and would be a lot more fragile than a metal one. That might be ok for light use, but stick it out in the battlefield and i dont see it holding up for long.
Might work disguised as a neon 'eat at joes' lamp for undercover work..
It also mentions needing several 'segments' to prevent jamming. Couldn't this also be done with more traditional antennas?
---- Booth was a patriot ----
Isn't plasma hot? ie:
1. Shoot radar-guided missile
2. Shoot heat-seeking missile
3. ???
4. Kaboom!
So good idea in theory, but hard to put into practical terms. I then guess the large power constraints and the fragility of the plasma are what's keeping this from commercial use. I know there was a post about cell phones using this. When thinking about powering the plasma I guess that gets thrown out the window.
I got a catholic block.
If it is performing as an antenna then it will have the same RF characteristics as a physical antenna and so must be open to jamming.
Engineering is the art of compromise.
The light is easily taken care of, just paint it black. The heat released is about the same as a fluorescent bulb, much less than a human being emits.
As for detecting the wire, an antenna is resonating at a specific frequency, and that can be detected easily with very simple equipment. That how most anti-shoplifting devices work.
I think the main use for these plasma antennas wouldn't be for a soldier in an open battlefield, but for covert operations instead. The idea is to make it harder for the enemy to find if someone in a crowd is carrying a concealed radio.
If you have seen Britney Spears face reacently, maybe those "sand niggers" as you like to call them maybe on to something
Make SELinux enforcing again!
Aircraft have been dealing with the problem of heat signatures produced by engines for a long time. Will this antenna really get as hot as the engines on an F-22?
This is an old idea. Look in Kraus, Antennas, Third edition. Section 21-29. Also see patent 6657594. The point is the RCS of the antenna is lower when the plasma is off, they efficiency of this type of antenna isn't that high.
This might have a small physical cross-section on radar, but I'm not sure that's enough to compensate for the plasma... ...I work in an electronics lab, and occasionally we use a sputtering system - which generates a ball of plasma to transfer ions from one surface to another. Anyway, point being, when we do this, the guys next door, who do a lot of RF measurements, go absolutely nuts - because we've just screwed all of their instruments and currently-running measurements. (Incidently, between them and the plasma is an inch-thick steel chamber at near-vacuum, plus a thinner steel layer and a reasonably thick wall.)
So sure, it may not look like much when it's off, but it's like a giant pillar of electromagnetic flame when it's on. Still worth it?
But can I use it for filesharing, and just disappear when the RIAA comes sniffing around?
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
The real application for this might be in space. It's very hard to hide your satellite from the incoming kill vehicle if you have a huge antenna deployed. This technique could actually project a "ghost antenna" just off the satellite, and since this is not horse shoes, close does not count.
I'm aging rapidly, I bought a new game and had no idea if my machine was good for it.
I don't quite get the usefulness of this thing either - when it's turned on, there's bright glowing plasma, and when it's turned off, even though it doesn't have a long metal piece, it still has a lot of metallic support machinery, plus it's a glass tube that you need to haul around carefully instead of a metal antenna or rubber ducky that you can bang into things.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
I am a heat-seeking missile so I am really getting a kick out of these replies...
Sure, it's hard to spot when you turn it off maybe... does that make up for the fact that it looks like it glows like a goddamn spotlight when it's turned on, or am I missing something?
The plasma is contained in a glass, neon light, like tube.
I was picturing a 30-40' foot long spear of flaming hot plasma death that you could turn on your enemies to turn them into smouldering piles of charcoal....and radio in to mom at the same time!!!
...is "Antennae".
Wouldn't the flag already be technically burning? Hippies, 1 You, 0
Everyone who parks their car in NYC and other hostile environments wants an antenna that vanishes when you turn it off. Plasma probably wouldn't jam after a year of use like a retractable antenna, and might even clean the snow off your car, including the pile burying you from the street plows.
--
make install -not war
Well, the "stealth" antenna in the article is a huge, glowing tube. According to the article, the antenna is indeed made of "gas-filled tubes reminiscent of neon bulbs."
I wouldn't call an neon sign "essentially vanishes" when it's turned off.
There's no indication in the article that they can generate the plasma without a confining tube, but even if they could, like the Cheshire cat's grin without the cat, it would still be pretty conspicuous when it's on.
Reminds me of an old cartoon in Computerworld, back in the days when corporations had just standardized on IBM PCs and tried to prevent people from bringing in Macintoshes. An IT inspector is saying to a flunky "Desk, chair, filing cabinet, large glowing chef's hat--nope, no Macintoshes here."
"How to Do Nothing," kids activities, back in print!
Did you think that maybe they might put the neon antenna inside an opaque container? Also, the "stealthy" part refers to it's ability to hide from antenna detectors, not physical inspection.
sounds like it might find application in the area of phased-array radars.
The higher the technology, the sharper that two-edged sword.
If George Lucas taught us anything, it's that these things should make a whum, whum noise as they're moved around plus a kind of white noise crackling whenever they hit things.
That's hardly unobtrusive in a crowd.
I know what those words mean, but that phrase didn't make any sense.
"Nine times out of ten, starting a fire is not the best way to solve the problem." - my wife
Metallic antennas are excited by EM radiation (radio waves) of a proper wavelength. In turn, the antenna will re-radiate (transmit) a tiny bit of that energy, although very weakly, which can be detected. This is totally passive, which is how it is possible to build a passive repeater by simply running a wire between two directional antennas. It is also the general principal of how RFID tags work.
The stealth of this antenna is that it is non-metallic and will not react to EMF when switched off. It has nothing to do with how big the antenna is, or what color it is, or whether or not it emits light, which are all things people have been speculating about.
Dan East
Better known as 318230.
No, because to burn something has to oxidize. Plasma is not an oxidization effect. Hippies 0, him 1
Eh, if it's designed as a fragmentation kill vehicle, close certainly does count.
Install a listening device in an embassy meeting room. Records many weeks of conversations. Does not broadcast. Also has a radio receiver.
Prior to an electrical storm, drop a package on the roof using a rapid-descent parachute. It looks like a chimney or AC unit, with a large pole on top that functions as a lightening rod. The box sends a signal to the inside recorder that tells it to broadcast a burst of encrypted data to the box then when lightening hits the pole, it becomes a plasma attenna that can broadcast the data over a long distance. Oh, and the electricity from the lightening powers the whole operation. Then the box self-destructs on the roof.
Seth
$5 / month hosted VPS on linux = awesome!
You cannot post an article with the words "invisible" or "disappear" willy-nilly! You must be precise! Do you know how many salivating geeks are about to be very disappointed by TFA?
(The gas becomes non-conductive when it's off, so it's "invisible" to radar or something like that. The glass tube holding the gas is perfectly visible. It's not like some sort of light-saber thing.)
I'd love to see that antenna shatter during vibration tests. Any kid with a pellet gun can break that thing, so it sure won't be very useful to anybody nevermind the military.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
are we any closer to having a real lightsaber?
Anything can, could, and will happen.
Anybody else thinking lightsaber? (Yeah, I'm jacking the thread, but it's not been mentioned yet.)
Linux, you magnificent bastard, I read the fucking manual!
If it's plasma, it's heated. Heat is highly visible to anyone using thermal imaging goggles on the ground, or in the air. Thus, not stealth.
Furthermore, the noise this thing produces will stand out like a sore thumb for a HARM (High speed Anti Radiation Missle) missle.
There is no reason it needs to be any noisier than a F40 florescent tube. Last time I checked, neon signs and florescent lights didn't attract HARM missiles. These tubes can be sensitive to HF and VHF while excited by DC or low frequency square wave AC. HARM missles due to the limited size of the RF direction finding is mostly limited to Microwave and UHF. HARM missiles mostly target microwave facilities, satellite uplink sites and radar. They are pretty blind to AM radio and lower frequency HF due to antenna size limitations.
The truth shall set you free!
a vacuum also conducts electricity .Maybe not as well.could they use a vacuum?
Only when there is a source of free electrons nearby. A CRT works by having an electron gun in the back. When it is dead, the electron flow stops. Add a small amount of gas and excite it and you have a low pressure plasma much like in a neon tube or plasma sphere. A vacuum is used as an insulator. Here is an example..
http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation_equipment/vacuum_circuit_breakers.html
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1601629
http://www.power-technology.com/contractors/switchgear/huayi/huayi5.html
no gas. no plasma. little arc from vaporised metal.
The truth shall set you free!
So, it 'vanishes' when it is off? When it is on it lights up like a neon sign? I could be wrong - but a gigantic neon light antenna up in the air is going to be a pretty obvious target. The enemy is going to know exactly where you are. Also - they are going to know you are transmitting something - so they can start to jam/home in on your signal. How exactly does this prevent that?
Also - I would love it if the enemy used this brilliant antenna design. You will be left flabber"gas"ted as I use my ultra-portable, ultra-stealthy jamming device to explode your plasma tubes on the battlefield. What is my weapon? A rock and a slingshot. My eyes! The goggles do nothing!
Seriously? You mean all I need is a Faraday cage to defeat them? Son of a bitch....
I remember seeing this stuff more than 10 years ago. Being Australian the stuff I saw ten years ago was from an Australian University grant from the DSTO (military research organisation), with information that can be found at http://wwwrsphysse.anu.edu.au/~ggb112/
In fact a Typical Fluroscent tube makes a reasonable HF antenna with its frequency dependent on its length. For those that think the glowing plasma makes the antenna detectable in the visible spectrum, its easy to have a material that is opaque in the visible spectrum but transparent in the radio spectrum. A piece of stryofoam is enough to do the job.
D.
In my mind, if you sell to the military, it's still commerce.
That was my very first thought too: if this is for military use anyway, then quit dicking around with making antennas and get busy on those sabers already! ;)
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