Thread: Antenna Amplifier Noise Figure
View Single Post
  #4   Report Post  
Old June 26th 15, 07:46 PM posted to sci.electronics.design,rec.radio.amateur.antenna
Tim Wescott[_6_] Tim Wescott[_6_] is offline
external usenet poster
  
First recorded activity by RadioBanter: Jun 2015
Posts: 1
Default Antenna Amplifier Noise Figure
On Fri, 26 Jun 2015 08:24:25 -0400, rickman wrote:

I read this post in an antenna group and I don't get how this guy is
coming up with a negative noise figure. Looks to me like he is
calculating the noise figure of a resistor, not the amplifier. Anyone
care to explain this to me?

The part that seems bogus is this...

The negative NF is defined as the amplifier noise being less than the
increase in noise due to the amplifier gain.

I thought noise figure was NF = SNRin / SNRout

Yes, it is. NF = 0dB is about as low as you can go without magic.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply With QuoteReply With Quote