How this calculator works
A reflected wave interferes with the incident wave to create standing-wave maxima and minima. VSWR is their voltage-amplitude ratio. Squaring the voltage reflection magnitude gives reflected power fraction for the same reference impedance. Return loss describes the reflected fraction; mismatch loss describes the reduction of accepted power. These quantities assume a passive load and do not specify the complex phase of the reflection coefficient.
Formula
VSWR = (1 + |Gamma|)/(1 - |Gamma|). |Gamma| = (VSWR - 1)/(VSWR + 1). Return loss = -20 log10|Gamma|. Reflected fraction = |Gamma|²; mismatch loss = -10 log10(1 - |Gamma|²).
Worked example
Reflection magnitude 0.5 gives VSWR 3, reflected power 25% and return loss 6.0206 dB. VSWR 2 corresponds to reflection magnitude 1/3 and reflected power 11.1111%.
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Frequently asked questions
Is return loss the same as insertion loss?
No. Return loss describes reflection toward the source. Insertion loss compares delivery before and after a device is inserted.
What happens at a perfect match?
Reflection is zero, VSWR is one and return loss is infinite. The limit is shown in text rather than as a non-finite number.
What happens with total reflection?
Reflection magnitude is one and accepted power is zero. VSWR and mismatch loss are infinite, which are shown as a text limit.