On Wed, 17 Sep 2003 05:10:40 GMT, Active8
wrote:

In article ,
says...
http://www.aftenposten.no/english/lo...ticleID=609108


Hmmm... sounds bogus to me.

somewhere in the jumble, i came across a theory/claim supposedly
originated by Nikolai Tesla. the theory being that applying a large
voltage - low freq. ac, dc... i don't remember - to a short antenna
would set up an electrically large antenna by virtue of the electric
field.

say you applied 1000V to a 1m whip. that's 1000V/m. or it's 1V/m over a
length of 1000m effective antenna length. that's the theory... key word
"theory".

An antenna has radiation resistance. If you deliver power into Rr, it,
well, radiates it. As an antenna gets smaller, its radiation
resistance increases, so to dump X watts into space using a smaller
antenna, you need to drive it from a higher voltage. P = E^2/Rr. One
gadget used to increase the voltage is an "antenna tuner", just a
resonant matching network. There are practical limits on how much
power you can force into a small antenna: skin effect heating,
ionization, matching network Q, stuff like that. Nothing mysterious
here.

John





brs,
mike