"Joel Koltner" wrote in
:

Here something I've been thinking about lately...

The idea of a noise figure N is, simply enough, how much loss in SNR
is seen going through a network (typically an amplifier) -- N =
(Si/Ni)/(So/No), expressed in dB. Say I have an antenna that I know
happens to provide an SNR of 60dB... if I feed that antenna into an

I meant to flag this statement.

Does it provide enough information for you to apply it in the way you
have?

It says nothing of the absolute noise power or signal power. You seem to
assume the noise power KTB noise where T is 290K.

What if you were pointing at directive antenna at cold sky, and Tnoise
was say 10K. (As a complication, no antenna is perfect, and there would
also be some spillover noise from the hot earth, but the total might be
well under 100K.)

Alternatively, what if you were talking about a HF antenna and say Tnoise
was say, 30000K.

Owen