Roy
I understand where you are coming from but your points are all based
around a Yagi with standard feeds !. In my past postings over the years
I have pointed out other methods of feeds that not only broaden the
bandwidth
but uses a high impedance, this done by extreme "close" coupling,
in the order of a inch or so upwards to about 12 inches which I also wrote
up
in a patent some years ago just for kicks.
I myself ,choose not to go less than 26 ohms when designing. and tho I can
make them with very high impedance it is not really required as the ham
bands
are quite narrow. Where I really concentrate upon is to move away
from "mutual" coupling ( what ever that means) which is commonly described
with yagi antennas, to "close" coupling designs which is an entirely new
world when
dealing with feed impedances, as Richards post on coupling some months ago
described so much better than I have done.

Regards
Art



"Roy Lewallen" wrote in message
...
There's yet another tradeoff -- bandwidth, of both the pattern and the
impedance. Close spacing, in particular, reduces the range of frequencies
over which the pattern is acceptable ("acceptable" being in itself subject
to compromise) and over which the SWR is acceptable. But close spaced or
not, it's much easier to tweak a design to work perfectly at a single
frequency than make one that will retain some semblance of that perfection
over a wider range of frequencies.

Roy Lewallen, W7EL

Richard Harrison wrote:
Art Unwin wrote:
"But my main question still remains a pointer to a technical article
that discusses the possibility or impossibility of what I have stated."

I don`t get the question, but it seems to me, Art wants to know if
anyone has written of a method to make maximum gain correspond with
maximum front-to-back ratio in a Yagi.
I haven`t seen it. There is a third factor in the compromise, 50-ohm
feedpoint (or some other convenient impedance).

snip.

Best regards, Richard Harrison, KB5WZI