"art" wrote in message
oups.com...
On 5 Mar, 20:41, Roy Lewallen wrote:
I should elaborate a little.

The average gain is the ratio of the total power in all directions at a
great distance (beyond the point where the surface wave has decayed to a
negligible value) to the power into the antenna from all the sources.
(There's a factor of two also involved when using a ground plane with
NEC but not with EZNEC.) So the average gain is the efficiency if you
consider ground reflection and the decay of the surface wave to be part
of the loss.

Roy Lewallen, W7EL

Lets have another look at this.

Roy inferred that the radiation field volume is the total useful
output

He then goes on to say that average gain what ever that means relative
to the final radiation field is the efficiency.
He also adds a condition relative to the definition of efficiency that
this is only true IF you count ground reflection and the decay of the
surface wave to be part of the loss


Hmmm I don't think anybody would deny that surface wave represents a
loss
relative to usefull work though some might say it contributes to
current flow, but why single out ground reflection as a loss since
that can be useful?
So Roy is classifying efficiency as something he considers usefull
and ground reflection is not usefull. He also throws average gain into
the equation without providing a definition of average
gain ( like gain is an advance over something he doesn't want to
state)
Jimminy cricket
I agree that you need to provide more elaboration

Why is it you can't say the useful result of what you provided is the
radiation volume where efficiency is useful output over input times
100?
Why does one have to place conditions on :

efficiency = useful output/ actual input x 100 ?

Seems like efficiency in radiation is not the same as efficiencies
in other sciences. Possibly a definition supplied by a related
commitee
solely for their own interpretation even though it is not in
accordance with other diciplines. Also possibly based on the number of
books on a particular shelf.And then the following week they placed
conditions to clarify what efficiency includes and does not include
such as certain portions of radiation, possibly with a different color
to the norm
phew

"Ground reflection loss" is probably a more precise term.

Frank