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.
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