"Roy Lewallen" wrote in message
...
Jerry Martes wrote:

Roy

I'm a real slopy builder. So, I do alot of half-assed things. I
might
begin with a 100 watt light bulb inside the "icebox" to establish a
referance temperature. maybe even a 50 watt and even a 25 watt. And,
if
the antenna could be modeled at some frequency where I could build an
ice
box thats sufficiently transparent to RF, like 6 Meters, I'd build a
full
size antenna for use as a referance.

I've never done something like this. It just sems very practical,
since a
100% efficient antenna wouldnt introduce any heat. But , a 50%
efficient
one might produce about the same heat as a 50 watt light bulb.

It would if the thermal mass of the antenna were the same as the light
bulb, and if the thermal loss through the wiring were the same for the
antenna as for the light bulb. But otherwise, they could be vastly
different.

I'd not declare this "ice box" to be a Lab Standard. But, if there
was
need, I'd sure try to evaluate the concept.

When people like you cast doubt on anything I tink up, I begin to
doubt
myself.

Jerry

Well, then I've done a good service. Only when you have doubts about
your methodolgy will you have any incentive to take the time to try and
understand what you're doing.

Any conclusions you reach about the antenna's efficiency (except that
it's not 100% efficient - duh) will be completely worthless unless you
get at least some kind of handle on the relationship between the heat
and the temperature.

Roy Lewallen, W7EL

Roy

Since I consider antenna efficiency difficult to measure accurately, I'd
be willing to try to measure it as carefully as *practical*. If that
required that the referance heater had a similar "thermal mass" to that of
the antenna under test, I could probably make a heater that did have a
thermal mass equivalent to that of the antenna.
But, I would propose that there is no easier way to actually measure an
antenna's efficiency than to measure the amount of power it turns into heat.
Thats a statement I cant back up, and I know it.

What is a better way to measure an antenna's efficiency??