S-Parameter Conversion Rechner — Formel

Understanding S-Parameters

Scattering parameters describe how RF energy propagates through a network.

Parameter Meanings

  • S11: Input return loss (reflection at port 1)
  • S21: Forward transmission (gain or insertion loss)
  • S12: Reverse transmission (isolation)
  • S22: Output return loss (reflection at port 2)

    • Conversion

    Linear = 10^(dB/20) (for voltage/amplitude)

    dB = 20 x log10(Linear)

    For passive devices, S21 is negative (loss). For amplifiers, S21 is positive (gain).

    Lösungsbeispiel

    A filter with S11=-15 dB, S21=-0.5 dB, S12=-30 dB, S22=-20 dB.

    1. S11 linear: 10^(-15/20) = 0.1778
    2. S21 linear: 10^(-0.5/20) = 0.9441
    3. S12 linear: 10^(-30/20) = 0.03162
    4. VSWR at port 1: (1+0.1778)/(1-0.1778) = 1.43
    5. Insertion loss: 0.5 dB