RF Converter: VSWR, Return Loss, Reflection and Mismatch Loss
Convert between VSWR, return loss, reflection coefficient and mismatch loss; dBm ↔ mW; wavelength in cable; simple link budget.
VSWR · return loss · mismatch
Enter any one value; the others update.
Impedance mismatch
Power conversion
Wavelength in cable
Cable & connector loss budget
Cable and connector loss values must come from the datasheets for your frequency. VSWR and return-loss relations: |Γ| = (VSWR − 1)/(VSWR + 1); RL = −20·log₁₀|Γ|; mismatch loss = −10·log₁₀(1 − |Γ|²).
Frequently asked questions
How do I convert VSWR to return loss?
First the reflection coefficient: |Γ| = (VSWR − 1) / (VSWR + 1). Then return loss = −20·log10 |Γ| dB. A VSWR of 1.5 gives |Γ| = 0.2 and about 14 dB; a VSWR of 2 gives |Γ| = 1/3 and about 9.5 dB.
What is mismatch loss?
Mismatch loss is the power that never reaches the load because of reflection: −10·log10 (1 − |Γ|²) dB. At a VSWR of 2 it is about 0.51 dB.
How do I convert dBm to milliwatts?
P(mW) = 10^(dBm / 10). So 0 dBm is 1 mW, 10 dBm is 10 mW and 30 dBm is 1 W.
For preliminary assessment only — the final decision must follow the manufacturer’s datasheet and the applicable NEC / IEC / UL standards. Results are calculated from the standard formulas stated on this page and are for design estimates only. They are not a rating of any specific part — always confirm current, voltage, temperature and environment limits against the manufacturer’s datasheet for the part you intend to use.
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