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SWR & reflection
Reflection coefficient, return loss and power fractions.
HB3YAQ · Ajdin HadzicLearning to take awayhttps://hb3yaq.ch/en/tools/swr
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Formula & context
|Γ| = (SWR − 1) / (SWR + 1); Pr/Pf = |Γ|²; RL = −20 log₁₀|Γ|
SWR compares voltage maxima and minima on a line. Squaring the reflection coefficient gives the reflected power fraction at one reference plane.
A worked example
SWR 2:1 means |Γ| = 1/3, approximately 11.11% reflected power and 9.54 dB return loss.
Assumptions & limits
Reflected power is not automatically heat loss. This is not a complete balance of transmitter, lossy feed line and radiation efficiency.
Interpreting SWR correctlyUnderstand the reasoning →From reading to experimenting
SWR & reflection
SWR 2:1 means |Γ| = 1/3, approximately 11.11% reflected power and 9.54 dB return loss.
Open example with starting values →Standing-wave ratio: 2 : 1 · Forward power: 100 WBack to the learning article →Then change exactly one value. Compare the result and use the formula to explain why it changes. The model limits below the calculator also apply here.