S-parameter calculation and export in Touchstone Format

EMC Plus may be used to calculate the scattering parameters matrix (S-parameters) of any arbitrary interconnection structure and export it in Touchstone format. The Touchstone file can be used in a circuit simulator together with other elements to evaluate the scattering parameters or the time-domain response of a complex circuit.

This demonstration model illustrates the workflow for calculating the S-parameter matrix of a coaxial cable and for exporting it in Touchstone format. This workflow includes setting up the problem space, assigning material properties, defining ports, meshing the model, performing the analysis, inspecting, and exporting the S-parameters. The geometry of a cable that connects the surfaces of a reference ground structure will be imported, the cable cross-section, made by a shield and one nested conductor, will be defined. The S-parameters will be calculated on the frequency range: 50 kHz – 1 GHz.

Next, the Touchstone file produced from this simulation is used to evaluate the time domain response of the coaxial cable. The cable, loaded with a 50 ohm resistor, is excited with a voltage source (rectangular pulse). The analysis is performed in the EMC Plus Nexxim Circuit modeling tool.

Finally, we perform the same analysis in EMA3D Cable without the steps of exporting a Touchstone file and running in the circuit model. Instead, this time it is simulated in EMA3D Cable’s full-wave EMA3D and transmission line MHARNESS co-simulation. We compare the results of the two approaches.

• Tutorial materials