S-Parameter Conversion Calculator

Convert S-parameter magnitudes between linear and dB, and calculate derived metrics like insertion loss and isolation.

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dB
dB
dB
dB

S21 Linear Magnitude

0.9441

S11 Linear Magnitude0.1778
S12 Linear Magnitude0.03162
S22 Linear Magnitude0.1000
VSWR at Port 11.43
Insertion Loss0.50 dB

S21 Linear Magnitude vs S11 (Return Loss at Port 1)

View formula & how it works →

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).

    Example Calculation

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

    1. 01S11 linear: 10^(-15/20) = 0.1778
    2. 02S21 linear: 10^(-0.5/20) = 0.9441
    3. 03S12 linear: 10^(-30/20) = 0.03162
    4. 04VSWR at port 1: (1+0.1778)/(1-0.1778) = 1.43
    5. 05Insertion loss: 0.5 dB

    Frequently Asked Questions

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