Touchstone.jl

Save and load network parameters in Touchstone® versions 1.0, 1.1, 2.0, and 2.1. Touchstone® is a registered trademark of Agilent Technologies, Inc.

Installation:

To install the latest release of the package, install Julia using Juliaup, start Julia, and enter the following command:

using Pkg
Pkg.add("Touchstone")

To install the development version, start Julia and enter the command:

using Pkg
Pkg.add(name="Touchstone",rev="main")

If you get errors when running the examples, please try installing the latest version of Julia and updating to the latest version of Touchstone.jl by running:

Pkg.update()

Then check that you are running the latest version of the package with:

Pkg.status()

Examples:

Load and save a Touchstone file

Version 1

julia> using Touchstone

julia> open("example1.s1p","w") do file
write(file,
"!Example 1:
!1-port S-parameter file, single frequency point
# MHz S MA R 50
!freq magS11 angS11
2.000 0.894 -12.136")
end

julia> example1 = touchstone_load("example1.s1p");

julia> example1.f, example1.N, example1.version
([2.0e6], ComplexF64[0.874020294860635 - 0.18794819544685323im;;;], 1.0)

julia> touchstone_save("example1_saved.s1p", example1.f, example1.N, version=1.0)

Version 2

julia> using Touchstone

julia> open("example2.ts","w") do file
write(file,
"!Example 1:
!1-port S-parameter file, single frequency point
[Version] 2.0
# Hz S RI R 50.0
[Number of Ports] 1
[Number of Frequencies] 1
[Reference] 50.0
[Network Data]
! freq ReS11 ImS11 
2.0e6 0.874020294860635 -0.18794819544685323
[End]")
end

julia> example2 = touchstone_load("example2.ts");

julia> example2.f, example2.N, example2.version
([2.0e6], ComplexF64[0.874020294860635 - 0.18794819544685323im;;;], 2.0)

julia> touchstone_save("example2_saved.ts", example2.f, example2.N, version=2.0)

Writing and validation

Use keyword arguments version=2.1 to write [Version] 2.1 files. Versions 2.0 and 2.1 share the same formatting rules. The constructor and array stream-writer defaults are version 2.0; the array file-save default is version 1.0. Saving a TouchstoneFile struct preserves the 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. The Touchstone 2.1 specification permits .ts for all versions and allows other extensions.

touchstone_save(filename, ts) and Touchstone.touchstone_write(io, ts) serialize ts.f (Hz), ts.N (network parameters), and metadata. They retain the version, representation, references, mixed-mode order, noise, information, and comments. Use the array forms to select metadata explicitly. Changing R or reference does not renormalize S parameters: the references must describe the supplied N. Similarly, mixedmodeorder describes the supplied data without performing a mixed-mode transformation. The object stores network data as f and N. ts.noisedata uses five values per frequency: frequency in the selected file unit, minimum noise figure in dB, reflection-coefficient magnitude, angle in degrees, and noise resistance in ohms.

Use RI or MA for exact zeros (not dB). Upper and Lower matrix formats require exact transpose symmetry. Use Full to preserve an asymmetric matrix. Inputs outside the representable Float64 range result in errors.

See CHANGELOG.md for compatibility changes.

Version 1 normalization

Version 1.0 files use one reference resistance R for all ports. Version 1.1 files allow one positive reference resistance per port at the end of the option line, for example # GHz S RI R 50 75. Use keyword arguments version=1.1, reference=[50.0,75.0] when writing a version 1.1 two-port file. The first reference sets R and normalizes the noise resistance. Files with multiple option-line resistances are identified as version 1.1 while files with a single resistance, including a one-port file, are reported as 1.0 files.

Loaded parameters use physical units. For file entries s, z, y, h, and g, with port resistances r1, …, rn, the conversions are:

Parameter	Physical value
Sij	sij
Zij	zij × sqrt(ri rj)
Yij	yij / sqrt(ri rj)
H11, H22	h11 × r1, h22 / r2
H12, H21	h12 × sqrt(r1/r2), h21 × sqrt(r1/r2)
G11, G22	g11 / r1, g22 × r2
G12, G21	g12 × sqrt(r2/r1), g21 × sqrt(r2/r1)

For version 1.0, every ri equals R, so H/G off-diagonal entries are unscaled. Noise resistance is returned in ohms. Versions 2.0 and 2.1 store physical parameters directly. These conversions follow the IBIS matrix-parameter derivation.

Contributing:

See source organization for implementation responsibilities and tests for the test layout and commands.

We welcome contributions in the form of issues/bug reports or pull requests. This project uses the MIT open source license.

References:

1. Legacy Touchstone specification, document revision 1.1
2. Touchstone v2.0
3. Touchstone v2.1