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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."
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.
Greetings,
It doesn't really prevent jamming, though it does give them a variable antenna, by tuning the plasma, thereby improving their ability rapidly change radio frequencies etc. This give them the ability to reduce the affects of single band jamming and even some multi-band jamming. It actually seems pretty clever, though, I really fail to see it's battlefield value as there will be a tremendous amount of heat given off by the plasma field. Now shipboard and some amored cav uses, I can see, but they have the ability to shield/mask the heat emissions.
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.
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.
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.
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!
As far as the micro fractures thing? That's not quite correct. What you get is a build up of internal stresses. This weakens the glass, and reduces it's ability to handle thermal and mechanical shocks. I may be mistaken, but I believe this is related to the coefficient of thermal expansion - basically as the outside of the glass cools it contracts. This leaves the cooled glass pushing against the pressure of the still molten glass, and once completely cooled, that stress remains.
That's all pretty much a non-issue though. Controlled cooling in an annealing oven takes care of it well enough.
>Borosilicate is pretty cheap, and I've seen rods of that thrown against a brick wall without taking any visible damage
Go you one better: Prince Rupert's Drops. Drip molten glass into water. The few that survive are incredibly, unbelievably tough -- I've made ones the size of peas (well, teardrop-shaped peas) and put them on a vise and hammered them with a steel hammer and left dents in the vise back and the hammer face, without hurting the glass. When that gets boring, you snap the long tail that was left when it fell off the main glob of glass, which sometimes takes a pair of pliers to snap even though it's hair-thin, and the whole drop explodes violently.
Don't bother trying to make a whole bunch and keep them in a box, though: the ones I made had a half-life of about 2 days.
I knew a chem grad student who dropped out because he spent all his grant money on special heat treatment stuff, dripping drops the size of lightbulbs off the roof of the chem building.
Nostalgia's not what it used to be.