"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."

Comments

embassy spying technology?

[SethJohnson]

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

Re:Hides by Glowing in the Dark?

[Palpitations]

You can fabricate some pretty sturdy pieces of glass that you could beat a person to death with, It's going to cost you a fortune but thats hasn't stopepd the military yet. If I remember correctly glass in theory is stronger then steel it's just that during the cooling process many micro fractures form in it. Strength and cost varies widely depending on the type of glass you use. Borosilicate is pretty cheap, and I've seen rods of that thrown against a brick wall without taking any visible damage (I didn't check it with a polariscope - a tool used to view internal stresses in glass). If you need something stronger you can use fused quartz, ruby, and I'm sure many more exotic forms.

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.