Touchstone® (SnP) converter
Touchstone® (SnP) Converter - using instructions
Upload the RF network data file with the extension ".snp", where n is the number of ports / interconnects in the network. Touchstone® file v2 with the extension ".ts" is accepted, but not tested. Select the data format type like decibel-angle, magnitude-angle, real-imaginary. Select the conversion format CSV / Spreadsheet / JSON or HTML.
Touchstone® (SnP) file format
Touchstone® file format [1] is the most commonly used file format for working with the Radio Frequency (RF) network parameter data. Also called SnP, where the n is the number of network ports (passive/active). Instruments like Vector Network Analyzers and RF circuit simulators use SnP as a de facto standard for working with network data values. The accepted file content is case-insensitive ASCII-formatted text. The comments and the noise parameter data is skipped while conversion.
When opened in an text editor, the typical SnP file [2] would look like below.
First few lines may have the comments preceeding with the exclamation symbol "!". Following that, The option line preceeds with the symbol "#". The option line format is # <frequency unit> <parameter> <format> R <n> . Where each parameter can have possible values as in the table below.
| Option line parameter | Possible options | Default | Comments |
|---|---|---|---|
| <frequency unit> | Hz, kHz, MHz, and GHz | GHz | Frequency range, 1st column |
| <parameter> | S for Scattering parameters, Y for Admittance parameters, Z for Impedance parameters, H for Hybrid-h parameters, G for Hybrid-g parameters |
S-Parameter |
Type of network data |
| <format> | DB for decibel-angle (decibel = 20 × log10|magnitude|), MA for magnitude-angle,RI for real-imaginary. The default format is MA. |
Magnitude / Angle | Angle unit is degree |
| R <n> | Reference reistance value in Ohm. | 50 Ohm | -- |
I felt that the SnP file's information is not spreadsheet-friendly. The frequency vs. network data columns aren't easily tabulated if you simply open the SnP file's contents in a spreadsheet. Additional processes, including deleting the comments, creating the headers, processing the de-limiters, etc., are necessary when exporting the SnP file for additional post-processing. For simpler post-processing, I believe it would be beneficial to have a tool that transforms SnP files into spreadsheet or CSV files. Because the data is saved in the matrix format for 3 port and higher number of port networks, it is difficult to manually translate SnP file into spreadsheet format, this tool may be useful in such requirements.
Reference:
[1] Touchstone® is a registered trademark of Agilent Technologies, Inc.
[2] HMC8413LP2FE - S-Parameters. Low Noise Amplifier from Analog Devices, Inc.
[3] Touchstone® File Format Specification
Acknowledgement:
[1] SnP file parsing is done by using scikit-rf, an open-source Python package for RF and Microwave applications.
