Engineering
VSWR & Return Loss Calculator
Calculate impedance mismatch metrics: VSWR, return loss, reflection coefficient, and mismatch loss for RF transmission lines and antenna systems.
Key Formulas
VSWR from Γ: VSWR = (1 + |Γ|) / (1 - |Γ|)
Γ from Impedance: Γ = (ZL - Z₀) / (ZL + Z₀)
Return Loss: RL = -20log₁₀(|Γ|) dB
Mismatch Loss: ML = -10log₁₀(1 - |Γ|²) dB
Power Reflected: Pr = |Γ|² × 100%
VSWR Interpretation Guide
| VSWR | Return Loss | Assessment |
|---|---|---|
| 1.0:1 | ∞ (ideal) | Perfect match, no reflection |
| 1.5:1 | 14 dB | Excellent—broadcast standard |
| 2.0:1 | 9.5 dB | Good—acceptable for most RF |
| 3.0:1 | 6 dB | Marginal—reduced efficiency |
| 5.0:1 | 2 dB | Poor—significant losses |