Extract from:

Microwave System Design Tools and EW Applications, Second Edition, by Peter W East.
Publisher: Artech House Inc, January 2008.

Cascaded Noise Figure

Applet Help

Applet Notes:

The applet calculates the cascaded gain, noise figure and noise temperature for up to four noisy components.
These components can either be amplifiers, (positive gain) or attenuators (negative gain). The applet adapts accordingly.
Components are ignored when both gain and noise figure are set to 0dB.

User Notes:
Noisy attenuating components such as mixers can be split into two components: the first simulating the loss (conversion loss, for example), and the second with 0dB gain simulating the excess noise (noise figure scrollbar set at the difference between the mixer noise figure and its conversion loss).
The equivalent overall Noise Temperature T is derived from the Noise Figure F using the relation: T = (F-1)T0, where T0 = 290°K, or T = (1/L-1)T0 for a noiseless attenuator with loss factor L.