Calculateur de Bilan de Liaison — Formule

## Friis Noise Figure Formula

### Formula

**F_total = F1 + (F2 - 1)/G1 + (F3 - 1)/(G1 x G2) + ...**

All values in linear (not dB). The first stage dominates overall noise figure. Use a low-noise amplifier (LNA) first for best sensitivity.

Exemple Résolu

LNA (1.5 dB NF, 20 dB gain) followed by mixer (10 dB NF, 15 dB gain) and IF amp (15 dB NF).

  1. F1 = 10^(1.5/10) = 1.413
  2. F2 = 10^(10/10) = 10, G1 = 10^(20/10) = 100
  3. F3 = 10^(15/10) = 31.62, G2 = 10^(15/10) = 31.62
  4. F_total = 1.413 + (10-1)/100 + (31.62-1)/(100x31.62) = 1.413 + 0.09 + 0.0097 = 1.513
  5. NF = 10 x log10(1.513) = 1.80 dB