Re "it does not agree...".When you look at the main characteristic of a
yagi antenna which is the gain of the main lobe and then compare it
with the rest of the radiation field then I would say it is
inefficient. I sure wish I had a picture of all the radiation vectors
that go into the shaping of the field. I did a circular pattern array
the other day where a circular cone was radiated vertically and I
thought that was as close to a beam that I ever had seen but why it
formed that way is a mystery. Frankly I feel the major need nowadays is
a broard beam as possible for line of site use for wireless devices
where the gain is constant for excess of 90 degrees coverage plus
large bandwidth rather than a emphasis on gain itself
Art

Richard Fry wrote:
"art" wrote in message
Some time ago I mentioned how inefficient Yagi design
antennas were thinking more in the way of how little of
the radiation used got to its required direction. etc
_________________

The above statement does not agree with the measured patterns and
performance results of Yagi antennas.

A well-designed, 6-element Yagi has a peak gain of at least 10 dBi, which
means that it radiates about 6.3 times more power in that direction than if
the same input power was radiated by a reference 1/2-wave dipole, and
measured in its direction of maximum gain.

RF