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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.
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
These antennas sound interesting, reconfigurable and all that, but I am guessing that their noise performance must be awful. And I mean electrical noise not audio noise for those out there who are confused. Usually in an RF system you want as little noise up front as possible, and noise goes up with temperature. So this is an antenna made of very hot plasma as the very first element in the receiver system.
I could be wrong, I didnt RTFA.
-Brandon
Quitters never win, Winners never quit, But those who never win and never quit are idiots.
Yes - and no :)
The gas is hot, but at very low pressure. So the amount of energy transmitted to the glass container surrounding it is minimal, and could be further reduced by active cooling. So the second your incomings are detected and the antenna shuts down it becomes invisible to both the RF and infrared seeker.
I'm aging rapidly, I bought a new game and had no idea if my machine was good for it.
I assume that the technology would be more useful in radar sources, where you could do a short term illumination of a target and then turn it off. A sensor trying to pick up the antenna when it was not powered might well have a significantly harder time than with a traditional antenna.
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.