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Hi Igor,

S-parameters are power ratios of some kind of ports with some kind of transmission in between. How would that look like in mf in your case?

Cheers Edgar

Hello Edgar! This question is because I need to simulate a system about wirelles power transfer using ressonant coils and it's will be operate in frequency around 1 MHz. Therefore, to correct avaliate about the eficiency of system, the S-parameters is going to more useful. Furthermore, with the S-parameters I can verificate if the minimum value S11 will be occur in the ressonance frequency.

In a transmission line system the S parameters are defined as ratios between incoming and outgoing waves. Those waves can be expressed in terms of the terminal voltages and currents. So if you have a calculation that yields terminal voltages and currents (for example, mf or es physics) you can calculate S parameters (which will be dependent on the transmission line impedance assumed). It is easy enough to calculate the S parameters in post-processing although they are not a predefined quantity in mf physics.

You can find the definitions for the waves and the S parameters in the usual textbooks or on the web.

(It is interesting that the waves are referred to as power waves despite the fact that they have the dimensions of voltage in many definitions).

It is also worth remarking that, if you use the Lumped Ports in a frequency-domain Magnetic Field model, the S-parameters are automatically calculated.

Note, though, that the Magnetic Fields interface is only for the modeling of NON-radiating structures, so it would likely be preferrable to use the Radio Frequency interface for this, since that includes the PML and SBC conditions that model boundaries to free space. Using the Magnetic Fields interface for computing S-parameters is primarily appropriate if dealing with non-radiative devices.

Happy Modeling!