[TowerTalk] Folded dipole

[jimlux]

Tom Osborne wrote:
> Hi All
> 
> Looking to put up another 40 meter antenna.  Need a NVIS antenna for 
> close-in work.
> 
> Is there any reason to put up a folded dipole instead of a tuned-feeder 
> dipole?
> 
> I think when this antenna was popular, it was touted to have more bandwidth 
> than a dipole.  But, if you have to use an antenna tuner to tune it anyway, 
> there doesn't seem to be any advantage over a regular antenna, bandwidth 
> wise.  73


The folded dipole *might* get the impedance to a better value for the 
tuner.  To a first order, a folded dipole has 4x the feedpoint impedance 
of the straight dipole.

If you were talking about the terminated folded dipole (e.g. the things 
from B&W, among others), then the loss in the antenna makes it a 
broadband unit without a tuner.

A lot of practical systems use the lossy dipole approach so they don't 
have to use a tuner, and just make up for the loss with a bigger power 
amp.  If you have a wide band to tune over (e.g. supporting emergency 
comm with a NVIS antenna, and you might have to tune anywhere) this 
isn't a bad approach.