Frank Donovan wrote:
> Anyone out there interested in high performance monoband Yagis???
> I'll prime the pump by sharing the YO file for my 6 element 15M beam on a
> 48 foot boom. Of course, I have YO files for all of my Yagis, and if
> there is sufficient interest, I'll post the YO files for my 40, 20 and
> 10M Yagis.
(If there is a YO reflector where this thread would be more appropriate I do
not know of it and I apologise for the bandwidth.)
I would certainly be interested in your YO designs. I have worked with 10
meter beams in YO and then built them with spectacular results. In Texas,
the prevailing school of thought was to build them for max gain forgetting
the front to back because we have no one behind us. However, after talking to
some big gun VHFers out at Field Day, I have decided that on 10 meters this
is the wrong approach. I believe there are many times that the noise level
is 10 to 20 db higher off the back of the beam over the desired direction.
With a 10 db or less F to B weak signals in the desired direction could be
masked. Now I shoot for more than 20 db F to B. This has had an added
benefit of making the beam designs look more "normal" to me. I guess after
40 years I have developed a "feel" for how an antenna should look, much the
same as being able to tell a friend where to tap a tower for a gamma match by
what "looks right."
I think that when you set a YO parameter to "0" you can run the risk of
having the program reach a result that is an extreme and will not work. I
have also found that, with close to optimum boom lengths for the number of
elements, designs with good front to back sometimes exhibit gain peaks at the
same frequency as the F to B peak.
Well, I could go on and on...
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