[Elecraft] dipole antenna efficiency

[Ron D'Eau Claire]

Ha, ha! Check the date on the article. 

VK5BR has a parallel tuned circuit (two plates for the capacitor and coil
for the inductance) with the "feed" tapped across a couple of turns of the
coil. 

One could use any parallel coil/capacitor combination with adequate voltage
and current ratings to do that. 

It's all fed with RF from the unbalanced open wire line, which certainly
does radiate a bit. The coil/cap combination will add a tiny bit of
radiation too. 

It reminds me the famous "light bulb" antenna by, if I recall correctly,
Larson E. Rapp, aka Byron Goodman, W1DX (SK) in which a feed line was
connected to an incandescent bulb atop a fence post in a much earlier April
issue of a well-known Amateur radio journal.

VK5BR's antenna might radiate a bit more, due to none of the energy being
converted to photons at visible light frequencies, but Rapp's version
offered a clear visual indication that the antenna was getting RF power.

Rewriting Maxwell's laws is a long-standing, honored tradition in many
electronics journals every April, Amateur and Professional.  

Ron AC7AC 



-----Original Message-----
Ooops.  I must apologise for my mistake:  I've read the article in more 
detail and Lloyd is not feeding a small antenna, he is using the "feeder" as

the antenna by deliberately unbalancing it with a terminal unit to obtain 
maximum current at the far end of the feeder.  Presumably this would then be

elevated to a convenient point for maximum effect.

David
G3UNA

> Here is an interesting antenna made by Lloyd Butler VK5BR.  It uses
> open
> wire feeder to a VERY small antenna.
>
> http://users.tpg.com.au/users/ldbutler/ReverseFeedTopLoading.htm
>
> David
> G3UNA
>