Allow frequency-dependent lumped port impedance (vector input) #553
Description
🚀 Feature Request: Allow frequency-dependent lumped port impedance (vector input)
Summary
Currently, AWS Palace requires a fixed RLC definition for lumped ports.
This limitation prevents accurate modeling of components whose impedance varies significantly with frequency — such as varactor diodes, tunable matching networks, or MEMS capacitors.
I propose enabling the lumped port definition to accept frequency-dependent impedance data, either directly as a vector (Z(f)) or via an imported file.
During a frequency sweep, Palace would then interpolate the provided impedance values to apply the correct boundary condition at each frequency point.
📚 Background and Motivation
In RF and microwave simulations, it is common to model devices such as varactor diodes or nonlinear tuning elements using equivalent small-signal impedances extracted from circuit models or measurements.
These impedances are strongly frequency-dependent even under a fixed bias condition due to parasitics (series Ls, Cp, Rs, etc.).
When performing a full-wave sweep in Palace, we can only specify a single R, L, and C value.
This forces the user to fit a static equivalent circuit over a finite band which introduces significant errors outside the narrow fit range.
In practical use cases (e.g., varactor-tuned filters, reconfigurable antennas, or harmonic balance verification), this becomes a serious limitation.
🔍 Desired Behavior
The lumped port definition should optionally accept a frequency-dependent impedance.