<<I do not understand the problem measuring low power.
Certainly we do not do it with a Bird, but we make receiver
measurements in the microwatt range all the time with little
question. There are many instruments that measure RF voltage
accurately, and if we know impedance (which is not hard to
determine) presto we have the power.>>
I think what Brett is referring to is the accuracy of the
Agilent spectrum analyzer. I think I actually have one of
the same models around here, and there should be a published
accuracy.
As I recall my Agilent analyzer is within a fraction of a dB
of my other calibrated instruments over most of it's range,
but of course that isn't saying they all are. This is a far
cry from older spectrum analyzers like the HP-141's and such
found in Hamshacks that are lucky to within a few dB, and
maybe the older analyzers are what causes the concern.
In any event since no one knows pattern or antenna
efficiency within several dB and since path loss is not
linear with distance, it really isn't worth worrying about
15dB power error.
73 Tom
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