Touchstone.jl

Read and write Touchstone 1.0, 1.1, 2.0, and 2.1 network-parameter files.

Quick start

using Touchstone

ts = touchstone_load("network.s2p")
frequencies = ts.f                 # Hz
parameters = ts.N                 # port × port × frequency

touchstone_save("network.ts", ts)

N contains physical network parameters: S is dimensionless, Z is in ohms, and Y is in siemens. H/G mix impedance, admittance, and dimensionless entries. The reader converts normalized version 1 values to these units. The frequencyunit field describes file frequencies; it does not change the Hz units of f. Noise frequencies retain the file unit, and noise resistance is in ohms.

Saving a TouchstoneFile retains its version, representation, and metadata, including mixed-mode order and noise data. Use the array form when selecting a new file representation explicitly.

Use Touchstone.touchstone_parse(io) and Touchstone.touchstone_write(io, ts) for streams. The writer uses the current f, N, and metadata. RI and MA can represent exact zeros; finite DB text cannot.

Versions and references

Version 1.0 uses one reference resistance R for all ports. Version 1.1 supports a resistance per port on the option line. To write the single-ended two-port data above as version 1.1 while retaining its references:

touchstone_save("network-v1.1.s2p", ts.f, ts.N;
    version=1.1, parameter=ts.parameter, reference=ts.reference, format="RI")

The supplied references describe N. Changing R or reference does not renormalize S parameters. For example, use reference=[50,75] only when the supplied S data already uses those references. Likewise, mixedmodeorder describes the supplied data; it does not perform a mixed-mode transformation.

For 1.1, reference[1] supplies R and the normalization of noise resistance. Multiple option-line resistances identify version 1.1 on reading. A single resistance, including a one-port file, is reported as version 1.0. Versions 2.0 and 2.1 use [Reference] for port references and store non-S parameters directly in physical units. Select version=2.1 to emit [Version] 2.1; both version 2 markers use the same data rules. Reading preserves the declared version.

Explicit filename extensions are preserved. When no extension is supplied, .sNp is appended for versions 1.0 and 1.1, and .ts for versions 2.0 and 2.1, where N is the number of ports. These defaults follow common naming conventions; the Touchstone 2.1 specification permits .ts for all versions and allows other extensions.

API

The supported interface consists of TouchstoneFile, touchstone_file, touchstone_load, touchstone_parse, touchstone_save, and touchstone_write. Only load/save are exported; use the Touchstone. prefix for other names. See the API reference for arguments, defaults, units, and validation. The implementation helpers in the internal reference may change.

The README includes normalization formulas and file-writing guarantees. See the changelog for migration requirements.