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NEC3 was superseded by NEC4, which is licensed from Lawrence Livermore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 <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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