Applet Notes:

The applet calculates the effective noise figure for up to four receiver chain components.
The 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 noise figure and conversion loss).

Applet Help