Tom it is no good plonking me for what david is saying because he is
not quoting me, in fact some of it is a requote of what he said not me.
I think he is creating a straw man that he can argue with, is that what
you call reality? He has spent most of his time in space and I believe
him

Tom Ring wrote:
Dave wrote:

SNIPPED

Art, It has absolutely NOTHING to do with measurements, or with 95 watts
or 5 watts, or antenna patterns, or the reactive components.

It is defining efficiency properly!

Net radiated power divided by power input is Efficiency. Measure it or
calculate it any way you want!

An antenna with -3 dB loss is a 50% efficient antenna independent of the
actual input power. Choose any power input you like. An antenna with -3
dB loss is a 50% efficient antenna regardless of gain, directivity,
antenna patterns, patents, claims, marketing Bull S--t, or anything else.

Put your favorite antenna inside a sphere of any suitable diameter that
contains the antenna. The total rf power coming out of the sphere
divided by the total rf power into the antenna [sphere] is the antenna
efficiency. There is NO OTHER definition!

Reducing power in the back and side lobes has absolutely NOTHING to do
with efficiency. It has to do with directivity.

Design of a Yagi, traps, conductors, element spacing etc. will produce
variations in gain, directivity, efficiency [variations in losses,
heat]. Practically, the difference in efficiency between a 90% efficient
antenna and a 98% efficient antenna is swamped by variations in the path
loss physics.

I spent years of my life designing rf systems for telemetry from space
vehicles through reentry to a ground station. Data integrity at the
ground station was and still is the dominating requirement. Based on
allowable data error rates, the total path equation required S/N ratios
of 12 dB or more. The solution is a systems solution where the minor
variations in antenna efficiency get lost in the calculations.


Art doesn't care about reality, he thinks he can create a new one which
ignores physics. You are wasting your time.

I am plonking this thread, and art.

tom
K0TAR