pysmithchart 0.9.0

A Python library extending Matplotlib to generate Smith Charts.

pysmithchart is a Python library that provides high-quality Smith charts for RF and microwave engineering applications. Built as a native extension to matplotlib, it enables reproducible analysis and publication-ready visualization of reflection coefficients, impedances, and admittances commonly encountered in transmission-line theory, antenna characterization, and network analysis.

Smith charts remain a foundational tool in RF engineering, and this library is designed to support both instructional use and research workflows. By integrating directly with matplotlib’s projection system, pysmithchart enables familiar plotting syntax while offering fine-grained control of chart geometry, grid styling, interpolation, and layout.

This project originated from pySmithPlot by Paul Staerke. It has been completely rewritten so any issues are not his.

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Features

• Seamless matplotlib integration — implemented as a projection; compatible with standard plotting workflows

• Support for common RF quantities — reflection coefficients, impedances, admittances, and S-parameters

• Configurable analytical grids — control spacing, style, and precision of constant-R and constant-X curves

• Interpolation utilities — optional smoothing and resampling of complex-valued datasets

• Custom marker rotation — useful for frequency-indexed trajectories and multi-point measurement data

• Publication-quality output — full control over fonts, colors, annotations, and line styling

Installation

Using pip:

pip install pysmithchart

Using conda:

conda install -c conda-forge pysmithchart

Quick Start

Reflection Coefficients (S-Parameters)

import matplotlib.pyplot as plt
from pysmithchart import R_DOMAIN

S = [0.5 + 0.3j, -0.2 - 0.1j]

plt.figure(figsize=(6, 6))
plt.subplot(1, 1, 1, projection="smith")
plt.plot(S, domain=R_DOMAIN, marker='o', markersize=10, label='S₁₁')
plt.legend()
plt.title('Reflection Coefficients')
plt.show()

Normalized Impedance Example

import matplotlib.pyplot as plt
import pysmithchart

ZL = [30 + 30j, 50 + 50j, 100 + 100j]

sc = {"grid.Z.minor_enable":True}
plt.figure(figsize=(6, 6))
ax = plt.subplot(1, 1, 1, projection="smith", Z0=200, **sc)
plt.plot(ZL, "b-o", markersize=10, label='Load Impedance')
plt.legend()
plt.title('Impedances with Z₀ = 200Ω')
plt.show()

Documentation

Comprehensive documentation, including the API reference, tutorials, theoretical background, and worked examples, is available at:

https://pysmithchart.readthedocs.io

A live, browser-based environment powered by JupyterLite is available for experimentation without installation:

https://scottprahl.github.io/pysmithchart/

License

pysmithchart is released under the BSD-3 Clause License.

Citation

If you use pysmithchart in academic or technical work, please cite:

Prahl, S. (2026). pysmithchart: A Python module for Smith charts (Version 0.6.0) [Computer software]. Zenodo. https://doi.org/10.5281/zenodo.8370821

BibTeX

@software{pygrin_prahl_2026,
  author    = {Scott Prahl},
  title     = {pysmithchart: A Python module for Smith charts},
  year      = {2026},
  version   = {0.6.0},
  doi       = {10.5281/zenodo.8370821},
  url       = {https://github.com/scottprahl/pygrin},
  publisher = {Zenodo}
}