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NEC3 was superseded by NEC4, which is licensed from Lawrence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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