Cascaded Noise Figure Calculator

Calculate total system noise figure using the Friis formula for a chain of RF stages.

What is cascaded noise figure?

Like a chain of people whispering a message — each person adds a little confusion and garbles the original slightly. Noise figure tells you how much "confusion" (noise) each stage of your receiver chain adds. The Friis formula calculates the combined effect of the whole chain.

Why does this matter?

In satellite receivers, the first amplifier (LNA) is the most critical component — it sets the noise quality for the entire chain. A noisy first stage cannot be fixed by later stages. That's why satellite dishes have a low-noise amplifier right at the dish, before the long cable run.

Stage Chain
Add stages in signal-flow order. Each stage needs a gain and noise figure in dB.

First stage — this dominates the total noise figure. Use the lowest-noise component here (e.g., an LNA).

Add preset:

Total NF
1.14 dB
Total Gain
13.00 dB
Cumulative Results
NF and gain accumulated through the chain.
StageStage NFStage GainCum. NFCum. Gain
1LNA
1.00 dB20.00 dB1.00 dB20.00 dB
2Mixer
7.00 dB-7.00 dB1.14 dB13.00 dB