VSWR / Return Loss / |Gamma|
Fast conversion with mismatch loss and power ratio metrics.
- VSWR = (1 + |Gamma|) / (1 - |Gamma|)
- RL(dB) = -20 * log10(|Gamma|)
- ML(dB) = -10 * log10(1 - |Gamma|^2)
Engineering Notes and Practical Use
This calculator is intended for fast conversion between the three most common mismatch indicators: VSWR, return loss, and reflection-coefficient magnitude. In day-to-day RF work, teams often receive one metric from a datasheet and need the other two immediately for acceptance limits, quick troubleshooting, or report consistency.
When to use each metric
- VSWR: popular in antenna and feedline documents where intuitive ratio interpretation is useful.
- Return Loss (dB): common in specifications and compliance limits because dB scales are easy to compare.
- |Gamma|: useful in calculation workflows, especially when combining mismatch effects mathematically.
Quick examples
- VSWR 2.0: |Gamma| = 0.333, RL about 9.54 dB, reflected power about 11.1%.
- RL 15 dB: |Gamma| about 0.178, VSWR about 1.43, reflected power about 3.2%.
- |Gamma| 0.1: VSWR about 1.22, RL 20 dB, delivered power about 99%.
Validation and caution
Results here are algebraic conversions from ideal equations. Real systems can differ because of connector repeatability, fixture de-embedding quality, calibration plane errors, and frequency dependence. For design freeze or production release, use calibrated measurement data as the decision source.
FAQ
- Can return loss be negative? In standard mismatch context, practical RL is treated as 0 dB or higher.
- Why is VSWR infinite at |Gamma| = 1? That point means total reflection and no delivered power to the load.
- Is low VSWR always enough? No. You still need to verify gain, efficiency, linearity, and thermal limits.