read some papers

Today, I read some papers, but I cannot find something helpful to use the relationship among frequency, conductivity and permittivity creatively.

Summary:

one method to predict permittivity is:
1. simulate magnitude and phase with FDTD (imputs are real and imaginary part of permittivity)
2. use magnitude and phase as inputs and permittivity as outputs to train the ANN model
3. measure other magnitudes and phases of different materials
4. use data from step 3 and model from step 2 to predict permttivity

another method to predict permittivity is:
1. obtain inputs from elementary measurements
2. build functions of permittivity and locations (linear, quadratic and Gaussian function) for different samples
3. train an ANN model with locations as inputs and parameters of functions as outputs.
4. input other locations to the model and predict permittivity
5. obtain 2-D complex permittivity profiles

FDTD (Finite-difference time-domain method) is a numerical analysis technique used for modeling computational electrodynamics.