Owen Duffy wrote:
Whilst I have reservations about the design pics etc referenced, the
fundamentals of the Yagi itself look good, and with an impoved matching /
balun element, it looks like a practical high performance antenna. They
are certainly becoming more popular in this part of the world where most
home brew designs are DL6WU based (for good reasons, but peformance isn't
the principle goal).

An improved design could persue a more reproduceable balun that had an
adequately high shunt impedance on one side of the DE, or better, a
symmetric balun, and the shunt impedance was tuned out as part of the DE
tuning adjustment. The latter, if done properly, should result in more
symmetric current distribution on the DE, and pattern closer to that
modelled.

On that point, I am often somewhat amused at the out of hand dismissal of
gamma matches because of pattern distortion, and recommendation of
asymmetric baluns in their place. Symmetric baluns are just not very
popular with hams on VHF and UHF.

Owen

Interesting that you are among a group that uses the DL6WU designs.
They were very good for their day, but the K1FOs had better all over
performance, especially regarding wet weather degradation. And they
were around 20 years ago.

The T match combined with what I've always thought of as his "4 element
launcher" is pretty much bulletproof. I think he may have been the
first one to have the first director very tight to the DE, which had
very desirable effects.

All you had to do was splice the first 4 elements from one of his
designs onto a well designed group of directors and you had a great
antenna. OK, not quite that simple, but a good place to start.

And I agree on the gamma. I like the T, but have never been able to see
any real issues from a gamma. As a disclaimer, I only use gammas on 6m.

tom
K0TAR