For RF engineers · Windows

The S‑parameter workbench for Windows

TstoneLab opens Touchstone files instantly — plot, probe, and compare S‑parameters across files and panes, with the charts RF work actually needs.

Get it free on the Microsoft Store

.s1p.s2p.s4p.snpdrag in, chart out

TstoneLab showing an antenna measurement in four chart panes: S11 magnitude, phase, Smith chart, and VSWR

What it does

The everyday S‑parameter toolkit

Instant charts

Drop in a Touchstone file and get magnitude, phase, group delay, or VSWR in seconds — with markers, peak search, and hover readouts.

Many files, one view

Overlay any number of Touchstone files on a single chart to compare runs and revisions, split them across multi-chart layouts, or open a whole folder at once.

Smith charts

Read Γ, impedance, and admittance right off the Smith chart, and drag the adjustable VSWR circle to check matching against your target.

Differential (mixed-mode) views

Working with differential pairs? Convert 4-port single-ended data to differential and common-mode S‑parameters (Sdd, Scc, and the cross terms) in one step.

Time domain & port tools

Flip frequency data into TDR/TDT views to locate discontinuities along the line, and use Port Mapper to renumber ports or pull out subsets when the file order doesn't match the bench.

Publication-ready figures

DecoChart turns working plots into publication- and datasheet-grade figures — style templates, logo overlay, and one-click copy or PNG export.

Screenshots

A closer look

QuickChart with the hover probe reading S11 and S22 at 15.5 GHz — Hover any chart — every trace under the pointer reads out.

Marker table tracking four markers across S-parameter traces, shown in light theme — Up to eight markers with peak search and a live table — light theme included.

Mixed Mode Analyzer converting a 4-port file to differential S-parameters with selectable port pairing — 4-port to differential in one click — pick the port pairing, get Sdd/Sdc/Scd/Scc.

DecoChart template gallery with IEEE and datasheet chart styles — DecoChart templates for IEEE columns, datasheets, posters, and slides.

Power-integrity S-parameters from 5 Hz to 500 MHz on a logarithmic frequency axis — Log axes take PDN-style data in stride — here 5 Hz to 500 MHz in one sweep.

Touchstone Editor showing the raw file text with a live S-parameter matrix panel — The raw Touchstone text, with a live matrix readout at the cursor line.

Built-in MCP server

Talk to your measurements

MCP (Model Context Protocol) is the open standard that lets AI assistants use desktop apps as tools. TstoneLab ships with an MCP server built in — connect Claude or any MCP client once, and your Touchstone workspace becomes something you can ask questions in plain language.

Works with Claude and other MCP-compatible assistants · Read the setup guide

“Screen every file in the Antennas folder against S11 ≤ −10 dB up to 6 GHz.”

Claude · via MCPChecked 14 files — 12 pass. filter_rev2.s2p fails at 5.86 GHz (−8.4 dB) and diplexer_a.s2p at 5.91 GHz (−9.7 dB).

“Summarize coupler_demo.s4p.”

Claude · via MCP4 ports, 10 MHz – 26.5 GHz, 2650 points. Worst insertion loss is 3.1 dB near 24.8 GHz; return loss stays below −12 dB across the band.

Illustrative conversation — answers come from your actual files.

Beyond the viewer

Measure it, or simulate it

Instrument remote control

Connect VISA-compatible instruments and measure S‑parameters straight into the app over SCPI — the chart opens itself when the data lands. A dedicated SCPI editor handles custom command sequences.

S-parameter simulator

No data yet? Draw the network on a schematic canvas — R, L, C, transmission lines, stubs, quarter-wave transformers, even embedded Touchstone blocks — sweep it, and chart the result on Cartesian or Smith plots.

Put your Touchstone files to work

Free · Runs on Windows 10 and 11 · Distributed through the Microsoft Store