Calibration Standard Comparison
| Standard | Required Standards | Accuracy | Best For |
|---|---|---|---|
| SOLT | Short, Open, Load (50Ω), Thru | Good (−40 dB residual directivity) | Lab bench, coaxial connectors |
| TRL | Thru, Reflect (short), Line (λ/4 at f₀) | Very good (PCB-specific cal) | PCB trace reference plane calibration |
| LRRM | Load, Reflect, Reflect, Match | Excellent for wafer | On-wafer, GSG probe station |
| LRL (line-reflect-line) | Two lines of different length, Reflect | Very good for waveguide | Waveguide measurements, mmWave |
SOLT Calibration Details
12-term error model (2-port VNA): 3 forward error terms (port 1): Ed1, Es1, Er1 3 reverse error terms (port 2): Ed2, Es2, Er2 2 transmission terms: Et_fwd, Et_rev 4 isolation terms: Ei_fwd, Ei_rev, Eleak_fwd, Eleak_rev Each standard excites subset of error terms: Open: primarily reflection tracking (Er) Short: primarily reflection tracking (different phase) Load: primarily directivity (Ed) Thru: transmission tracking (Et) and source match (Es)
Calibration Kit Models
Real calibration standards are not ideal. The calibration kit model accounts for:
- Short: offset delay length (physical length of coaxial standard before short)
- Open: fringing capacitance C₀, C₁, C₂, C₃ polynomial
- Load: residual inductance and capacitance of 50Ω termination
RF View VNA Companion: After VNA calibration and measurement, load your .s2p files in RF View for S-parameter analysis, matching design, and Monte Carlo — on Android. The calibration accuracy of your VNA directly determines the accuracy of all subsequent RF View analysis. Free on Google Play.