On Sat, 09 Apr 2005 21:12:47 -0500, Tom Ring
wrote:
A 432 MHz antenna scrubbed with a
ScotchBrite showed a .6 dB gain increase.
So B as in B, S as in S, as we say here in Minnesota.

Hi Tom,

You could measure to the accuracy of better than 0.2dB between two
separate tests? And at UHF too? Care to share how?

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Sat, 09 Apr 2005 21:12:47 -0500, Tom Ring
wrote:

A 432 MHz antenna scrubbed with a
ScotchBrite showed a .6 dB gain increase.
So B as in B, S as in S, as we say here in Minnesota.


Hi Tom,

You could measure to the accuracy of better than 0.2dB between two
separate tests? And at UHF too? Care to share how?

73's
Richard Clark, KB7QHC

Well, you'd have to ask Mark Thorsen, WB0TEM, what equipment was used,
but the range is checked several times against the reference antenna
during each band we run, and is generally within .1 dB between checks.
Except that one day in KS. Boy was it hot.

I wouldn't bet absolute values are on the mark, but an antenna measured
against itself was reproducable. So I do believe the antenna improved
due to having the oxide scrubbed off.

tom
K0TAR

On Sun, 10 Apr 2005 09:23:19 -0500, Tom Ring
wrote:

I wouldn't bet absolute values are on the mark, but an antenna measured
against itself was reproducable.

Hi Tom,

But the point of accuracy, even reproducible accuracy, requires a very
absolute source to compare against. Sometimes that absolute is quite
simple to achieve, but now you have upped the ante to 0.1dB. This
implies a measurement accuracy of at least three times better; which,
in turn, means you have access to a standard that can discern 0.8%.

To say you test the antenna "against itself" does not really say much
when it comes to power and gain. That is no benchmark. The
presumption here is that you have an external source of power that is
constant. This then raises the same question. Over a span of time,
what guarantees this degree of accuracy? By what method is it
confirmed? That source's "absolute" power level needn't be an issue,
but there is no way to escape casting that "absolute" requirement into
another standard to confirm the fact of its stability.

73's
Richard Clark, KB7QHC