# Post-processing

PalaceToolkit includes modules for extracting and visualising simulation
results.

---

## Impedance extraction

Extract antenna input impedance from Palace port output files:

```python
from palacetoolkit.simulation import extract_impedance

freq_ghz, z_ant = extract_impedance("postpro/my_antenna")
```

This reads `port-S.csv`, `port-V.csv`, and `port-I.csv`, computes the
reference impedance $Z_0$, and returns the complex antenna impedance:

$$
Z_\text{ant} = Z_0 \frac{1 + S_{11}}{1 - S_{11}}
$$

## S-parameter plots

```python
from palacetoolkit.s_plot import plot_s_params

plot_s_params("postpro/my_antenna/port-S.csv")
```

Generates magnitude plots of $|S_{11}|$ (and $|S_{21}|$ when available)
versus frequency.

WSL note:
If plots do not open a window, install `python3-tk` and set matplotlib
backend to `TkAgg` in `~/.config/matplotlib/matplotlibrc`.

## Analytic reference values

Compare simulation results against closed-form expressions:

```python
from palacetoolkit.analytic import cpw_impedance, cpw_effective_index

Z0 = cpw_impedance(w=44e-6, s=25e-6, h=500e-6, eps_r=11.7)
n_eff = cpw_effective_index(w=44e-6, s=25e-6, h=500e-6, eps_r=11.7)
```

These use conformal-mapping formulas for coplanar waveguide (CPW) lines.

## 3D mesh visualisation

### Interactive viewer (notebooks)

```python
from palacetoolkit.viz import view_mesh

view_mesh("model.msh", transparent_groups=["air"])
```

`view_mesh()` now uses PyVista's interactive notebook backend when executed
inside Jupyter (including docs notebook runs), so the rendered mesh remains
pan/zoom/rotate capable in the generated documentation.