Dan, Bill, Guy
Thanks for your input...
It looks like the project may be too big in time and cost if NEC4
license is required. I will have to think further before committing.
Thanks again.
73,
Dave, G3UEG
At 00:01 26/01/2012, dan edwards wrote:
>to me, anyway, the OWA 'burns' a director for broad-band impedance
>matching..so, a
> '4 el OWA' is really a 3 element yagi...don't think the first
> director contributes much to
> forward gain or f/b.....K3LR & W3LPL have 40m monsters built that
> way....making a
> broad band yagi with gain very similar to a 3 el one...except with
> a better match across
> a wider freq. span...
>
>
>my $0.02 worth...73, w5xz, dan
>
>
>--- On Wed, 1/25/12, David Gould <dave@g3ueg.co.uk> wrote:
>
>From: David Gould <dave@g3ueg.co.uk>
>Subject: Re: [Antennaware] 3-element HF yagi design
>To: "Guy Olinger K2AV" <olinger@bellsouth.net>
>Cc: antennaware@contesting.com
>Date: Wednesday, January 25, 2012, 8:50 PM
>
>Guy,
>
>Thanks for the information. (I meant NEC-2 not NEC-3, and Yes, I
>appreciate EZNEC is not an optimiser.)
>
>Ok there would be some technical issues to resolve, but the main
>question still remains - whether there are any **fundamental
>reasons** why it is NOT be possible to design a 3-element yagi with
>a frequency independent feed? I have read a bit about OWA yagis, but
>I have only found reference to ones with 4 or more elements.
>
>73,
>Dave, G3UEG
>
>
>
>
>
>
>At 20:03 25/01/2012, Guy Olinger K2AV wrote:
> >EZNEC is not an optimizing modeler. So design iterations with the
> >model are manually directed.
> >
> >HF yagis from a standing start are best done with YO. Which, alas,
> >is not being marketed by Brian K6STI any more (unless someone knows
> >something new ??). Try USPS mail to Brian's QRZ.com address. I
> >will not expound the long story about how things got to be this way.
> >
> >EZNEC (with NEC2 engine) has a limited stepped diameter correction
> >mechanism, which is not part of the NEC2 process. Its limitations
> >would seem to fit an HF yagi.
> >
> >NEC3 was superseded by NEC4, which is licensed from Lawrence
> >Livermore Labs. See the wikipedia article. Only NEC2 and NEC4 are
> >available as processing cores.
> >
> >73, Guy.
> >
> >On Wed, Jan 25, 2012 at 12:55 PM, David Gould
> ><<mailto:dave@g3ueg.co.uk>dave@g3ueg.co.uk> wrote:
> >I would be interested in whether it is possible to design a 3-element
> >HF yagi (with tapered aluminium tubing) that has a frequency
> >independent feed. I am willing to compromise top-notch performance
> >for flexibility/simplicity. My thinking is to feed with a standard
> >ratio Balun (eg 50ohm or perhaps 25ohm)
> >
> >Does anyone already have a model for any of the HF bands (but 20m
> >would be preferred if available) that they would be willing to share?
> >
> >I don't know whether I am asking for the impossible here!!
> >
> >Second question.. Can I model such an antenna reliably with EZNEC+ 5
> >using the NEC 3 engine? (I have been advised that NEC3 is not good
> >enough and NEC4 is really needed.)
> >
> >73,
> >Dave, G3UEG
> >
> >
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> >
>
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