[Elecraft] folded dipole of topic

[Guy Olinger, K2AV]

----- Original Message ----- 
From: "Earl W Cunningham" <k6se@juno.com>

> Contrary to popular belief, the folded dipole has only about a 1%
wider
> bandwidth than a simple dipole (because of its "fatness").  The
> disadvantage of a folded dipole (need for a 4:1 balun when feeding
this
> 288-ohm antenna with 75- or 50-ohm coax) makes the simple dipole the
> better option.

There are certainly advantages of physical simplicity for the dipole.

HOWEVER, after rechecking some number of models and some old notes on
folded dipoles I have had in the air (which were quite broader than my
dipoles), I am very perplexed about your statement on the bandwidth of
a folded dipole. The rub on the FD's was that they were fragile, and
required maintenance. NOT that they didn't have extra bandwidth.

An 80 meter dipole at 75' shows a 1.5:1 bandwidth of 145 kHz, while a
folded dipole (double wire all the way) shows a 1.5:1 bandwidth of 205
kHz.  Approaching a 50% increase.

RELATIVE TO THE RESONANT FREQUENCY, that's a bandwidth of 4.12% for
the dipole and 5.95% for the folded dipole. Is THAT what you meant by
1% difference?

Whether the extra bandwidth is USEFUL is an individual call, but it's
not as if the dipole was 145 kHz and the FD was 147 kHz bandwidth.

73, Guy