S-Parameter Viewer
Parse a bounded local Touchstone subset and inspect magnitude, phase, Smith position, and group delay.
- Typical inputs
- Local .s1p/.s2p text in RI, MA, or DB form, parameter selection, and frequency marker.
- Calculated output
- Magnitude, wrapped/unwrapped phase, group delay, Smith position, and local CSV export.
- Model status
- Release D · documented and numerically tested
What do the file’s network parameters say at the selected frequency marker?
Local Touchstone inspection
The file is parsed only in this browser; nothing is uploaded or persisted. Strict grammar, size, line, port, and point caps bound malformed input.
ASCII · 2 MB · 100,000 lines · 20,000 points · 1 or 2 ports
- Ports / points
- 2 / 5
- Version / format
- 1.0 / MA
- Reference resistance
- 50.0000 Ω
- Unwrapped phase
- -108.0000°
- Group delay
- 100 ps
- Transmission interpretation
- 1.50000 dB loss
S21 is a transmission term: the sign above is named explicitly as loss or gain. Marker conclusions remain conditional on calibration, fixture removal, and the stated reference plane.
| Frequency | Magnitude dB | Phase | Unwrapped | Group delay |
|---|---|---|---|---|
| 1 GHz | -1.00000 | -36.0000° | -36.0000° | 100 ps |
| 2 GHz | -1.20000 | -72.0000° | -72.0000° | 100 ps |
| 3 GHz | -1.50000 | -108.0000° | -108.0000° | 100 ps |
| 4 GHz | -1.80000 | -144.0000° | -144.0000° | 100 ps |
| 5 GHz | -2.00000 | -180.0000° | -180.0000° | 100 ps |
Supported: .s1p/.s2p, Hz/kHz/MHz/GHz, S data in RI/MA/DB, comments, option line, one positive real reference, legacy two-port ordering, and the listed full-matrix Touchstone 2.0 subset. Rejected: arbitrary n-port, mixed-mode, noise blocks, per-port complex references, binary data, and 2.1-only constructs.
What this calculator is doing
A bounded parser converts declared Touchstone data to complex S-parameters, preserves legacy ordering, unwraps phase, and differentiates phase over angular frequency for group delay.
How to read the result
Inspect magnitude and phase together, retaining measurement plane, calibration, fixture treatment, port impedance, and file version. Smooth plots do not prove validity.
Equations & conventions
- Sij is outgoing wave at port i divided by incident wave at port j.
- τg = −dφ/dω uses unwrapped phase in radians.
- Arbitrary n-port, mixed-mode, and noise blocks are rejected.
Independently checked example
Checked example: the bundled linear-phase S21 sample represents 100 ps delay; central-difference group delay is 100 ps within numerical precision.
Common mistakes
- Assuming legacy two-port order is S11, S12, S21, S22.
- Differentiating wrapped phase or trusting an isolated endpoint.
Assumptions, validity & omissions
- Local parsing only; the file is never uploaded.
- Supports .s1p/.s2p RI, MA, and DB plus a tested Touchstone 2.0 subset.
- Mixed mode, noise data, and arbitrary n-port matrices are rejected.
Sources & model provenance
- IBIS Open Forum, Touchstone File Format Specification 2.0 (opens in a new tab) — Parser grammar and legacy two-port ordering. A deliberately tested subset; Touchstone 2.1 is current. Accessed 2026-09-05.
- Keysight, Understanding the Fundamental Principles of Vector Network Analysis (opens in a new tab) — Reflection, S-parameters, Smith charts, and group delay. Accessed 2026-09-05.