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VSWR / return loss converter

Convert between voltage standing wave ratio (VSWR), return loss in dB, and reflection coefficient magnitude |Γ|. Type in any one — the others update instantly.

Convert

:1
dB
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Common targets: VSWR 2:1 (RL ≈ 9.5 dB) is typical for consumer antennas; VSWR 1.5:1 (RL ≈ 14 dB) for tighter systems; VSWR 1.2:1 (RL ≈ 20 dB) for instrument-grade matching.

Power & loss

Reflected power —%
Transmitted power —%
Mismatch loss —dB
Reflected power —dB
|Γ|² (power reflection) —

Definitions

Reflection coefficient Γ describes the ratio of reflected to incident voltage at a discontinuity: Γ = (Z_L - Z_0) / (Z_L + Z_0). The magnitude |Γ| is between 0 (perfect match) and 1 (open or short).

VSWR is the ratio of maximum to minimum voltage along a standing wave: VSWR = (1 + |Γ|) / (1 − |Γ|). Always ≥ 1.

Return loss is the dB ratio of incident to reflected power: RL = −20·log₁₀(|Γ|). Higher is better — more "lost" back into the line means less reflected.

Mismatch loss is the power lost due to reflection: ML = −10·log₁₀(1 − |Γ|²). This is the actual penalty in your link budget from a bad match.

Quick reference

VSWR 1.0 = perfect match · VSWR 2.0 = 11.1% reflected, ML 0.51 dB · VSWR 3.0 = 25% reflected, ML 1.25 dB · VSWR 5.0 = 44.4% reflected, ML 2.55 dB · VSWR ∞ = 100% reflected (open/short).