Conversion Formula
S11_dB → |Γ| → VSWR:
Step 1: |Γ| = 10^(S11_dB / 20)
Step 2: VSWR = (1 + |Γ|) / (1 − |Γ|)
Example: S11 = −10 dB
|Γ| = 10^(−10/20) = 10^(−0.5) = 0.316
VSWR = (1.316)/(0.684) = 1.92 : 1Quick Reference Table
| S11 (dB) | VSWR | Application |
|---|---|---|
| −6 | 3.01 | Fail (most specs) |
| −10 | 1.92 | Minimum for most antennas |
| −14 | 1.50 | Base station spec |
| −20 | 1.22 | Good lab cable |
| −30 | 1.06 | Excellent component match |
Automated VSWR in RF View
- Load .s1p or .s2p file in RF View
- Select "VSWR" from the parameter dropdown (instead of S11 dB)
- Y-axis now shows VSWR directly (1.0 at bottom, higher VSWR at top)
- Activate BW Marker → set threshold to VSWR = 2.0
- RF View finds the bandwidth where VSWR < 2:1 automatically
RF View VSWR Display: One-tap switch from S11 dB to VSWR view. BW Marker reads VSWR < 2:1 bandwidth automatically. Free on Android.