On Wed, 10 Sep 2008 16:46:00 -0400, john Wiener
wrote:

I want to use this antenna for 30M but also for multiband use.
Thanks for correcting my fuzzy math.

I have read several articles that state inferiority of the OCF to the
dipole. Perhaps they are misunderestimating?

Hi John,

You have a problem with too many references with too little knowledge,
I'm afraid. Of course my own posting could easily fulfill that
dilemma, but that doesn't stop me from proceeding.

First off, the OCF is a dipole. And here begins what would be a
pointless debate of semantics into the meaning, definition, and quest
for what a dipole "is." As a dipole, it simply has a different
feedpoint placement along its length.

As it happens, that same wire will resonate at very nearly every
harmonic no matter where it is tapped: in the conventional middle, or
to one side by whatever degree. What changes by shifting that point
is the match of resonance.

Over the course of time, some wag either brute forced worked it out,
did a model, or thought he measured it to demonstrate that a certain
sweet spot, in combination with a 4:1 BalUn produced an antenna that
was a most useful connection to a rig for little further tuning.

In some large part, that is true. The devil is in the details
however, and those details are rarely discussed by the sons of that
cult of worship. You may well already be aware that such an antenna
is prone to Common Mode problems (otherwise claimed as benefits by
those who couldn't solve them); and these problems are directly
attributable to the off center (or unbalanced) state. As truth be
known, nearly every dipole is unbalanced to some degree, so this OCF
is more so, and deliberately more so.

How do people reconcile using their own common dipole with its
unintended unbalance? Choking. Hence the same admonition goes with
the OCF, by that greater degree of "more so." Thus if you can
successfully choke it, the OCF could bring you all the claimed
virtues.

Now if you only knew the location of that sweet spot drive point....

If you got this far, we go to that length too.

73's
Richard Clark, KB7QHC