Support frequency-dependent materials for 3D eigenmode simulations.

[WEIXUEP]

Hi,

I want to use frequency-dependent materials in 3D eigen mode simulation, the material may be defined as follows:

"PermittivityEqn": "2.08 + 0.0287629*ln((2.53303e22 + f*f)/(8.22935e9 + f*f))",
"ConductivityEqn": "1e-12 + 3.20031e-12*f*(atan(f/90715.7) - atan(f/1.59155e11))"

The variable f denotes frequency in Hz, consistent with the unit convention adopted in Ansys HFSS.

In most engineering scenarios, only permittivity and conductivity exhibit frequency dependence. For this iteration, only PermittivityEqn and ConductivityEqn are enabled. These equation-based definitions are mutually exclusive with the original fixed constant material parameters to avoid ambiguous configuration conflicts.

I have already implemented this feature in https://github.com/WEIXUEP/palace/tree/feature/permittivity-conductivity-eqn, and I’m wondering if this can be merged.

[hughcars]

Hi @WEIXUEP,

Thank you for your interest in palace, and interest in contributing to palace. That sounds like a feature that could be of interest to the broader user base. If you would like to open a PR we can start the process for reviewing and iterating on it.