"Mark Keith" wrote in message
om...
"Richard" wrote in message
...
"Richard" wrote in message
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Yet, I think whoever wrote note 688 expects a "designer" to put almost
whatever he wants for DE,

I'm not really sure about that. Maybe this is not expected, rather
perhaps
there is an implication DE ought to be a folded dipole.

I doubt I would use a folded DE myself. More work... Normally, I
would just use a grounded DE, but in your case, you need to consider
how you would tune the antenna. IE: gamma match, etc...If you have no
radio that transmits, or an antenna analyser, it might be tricky..In
that case, probably the simpliest method would be to use a split,
carefully cut dipole DE, and hope for the best. The dimensions,
spacings, etc, are critical yes, but I don't think as critical as you
think. IE: I don't really worry too much about element mounting
methods, etc, when I build a yagi. Almost anything you slap together
should work pretty well as long as you measured carefully. When I once
made one for that purpose, I didn't have a transmitter. And I did use
a gamma match. I had no decent way to tune it up. So I just
guesstimated, and tuned the match for max signal, noise, etc..I don't
know how well it came out as far as the match, but the antenna worked
great.
A simple fast way to design an NBS yagi for any freq, is to use the
eznec demo. It has a NBS yagi as a demo, and it can be easily scaled
for any freq. MK

Okay, but aren't these models only sufficiently accurate if you use the
dimensions in the models to build an actual yagi, if the boom is non
conducting? Is it not true that if the boom is conducting you cannot rely on
the model dimensions?