# rfx

> JAX-native electromagnetic simulation: manuals, reproducible examples and generated API reference.

Channel: development. Package version: 2.0.0rc1. Source commit: 2c32b7cf79b796fae825bfa08fc73d9914e61723.

Read the support boundaries before proposing a configuration. Importability, a successful run,
and a historical visualization do not establish accuracy or a supported gradient.

## API and support

- [Typed API inventory](https://remilab.ai/rfx/api/inventory.json): signatures, defaults, annotations, docstrings and pinned sources.
- [Deep API reference](https://remilab.ai/rfx/api/generated/rfx.html)
- [Support boundaries](https://remilab.ai/rfx/markdown/support.md)
- [docs/guides/support_matrix.json](https://remilab.ai/rfx/api/support/support_matrix.json)
- [docs/guides/sparameter_support_matrix.json](https://remilab.ai/rfx/api/support/sparameter_support_matrix.json)
- [Build manifest](https://remilab.ai/rfx/docs-manifest.json): source SHA and file hashes.
- [Combined manual](https://remilab.ai/rfx/llms-full.txt)

## For coding agents

- [AI Agent Overview](https://remilab.ai/rfx/markdown/agent/overview.md): How to use rfx public docs and support boundaries when asking an AI agent to build or review simulations.
- [Agent Auto-Configuration](https://remilab.ai/rfx/markdown/agent/auto-config.md): A conservative workflow for agents using rfx auto-configuration and preflight checks.
- [Agent Design Workflows](https://remilab.ai/rfx/markdown/agent/design-workflows.md): How agents should approach rfx design, sweep, optimization, and reporting workflows.
- [Port & Source Selection](https://remilab.ai/rfx/markdown/agent/port-selection.md): Decision guide for choosing the right rfx port, source, and S-parameter extraction primitive for each device class.
- [Agent Prompt Templates](https://remilab.ai/rfx/markdown/agent/prompt-templates.md): Reusable prompts for safe rfx simulation, validation, documentation, and review work.
- [Recipe: End-to-End Design Loop](https://remilab.ai/rfx/markdown/agent/recipe-design-loop.md): From device class to a gradient-optimized design with a validation verdict: port selection, AD-safe compute path, objective, optimizer, final checks, and unsupported paths.
- [Recipe: Failed-Gate Triage](https://remilab.ai/rfx/markdown/agent/recipe-failed-gate-triage.md): Decision tree for diagnosing a failed S-parameter or physics gate in rfx, with closed dead-end paths marked so agents do not re-attempt falsified fixes.
- [Recipe: Parameter Sweeps](https://remilab.ai/rfx/markdown/agent/recipe-parameter-sweeps.md): Choosing between parametric_sweep, vmap_material_sweep, and ntff_sweep — what each lane supports and where each one is the wrong tool.
- [Resonance Extraction](https://remilab.ai/rfx/markdown/agent/recipe-resonance-extraction.md): Select a source-off resonance measurement and use the supported ringdown API controls.
- [Recipe: Broadband R(f)/T(f) of a Slab or Scatterer](https://remilab.ai/rfx/markdown/agent/recipe-rt-measurement.md): How to measure broadband reflection and transmission spectra of a dielectric slab, multilayer stack, or dispersive scatterer using rfx flux monitors and two-run reference subtraction.

## Showcase results

- [Showcase catalog](https://remilab.ai/rfx/showcase/showcase.json): schema rfx-showcase-catalog/1; per case its page, the rfx commits, every file on the share host with its size and SHA-256, and each printed number with its value, unit and source.

- [Which cells move a patch antenna's match?](https://remilab.ai/rfx/markdown/showcase/sensitivity-map.md): catalog entry `sensitivity-map` in [showcase.json](https://remilab.ai/rfx/showcase/showcase.json); [patch-sensitivity/result.json](https://remilab.cnu.ac.kr/share/7c02ad43c580/patch-sensitivity/result.json)
- [What does a gradient cost?](https://remilab.ai/rfx/markdown/showcase/gradient-cost.md): catalog entry `gradient-cost` in [showcase.json](https://remilab.ai/rfx/showcase/showcase.json); [patch-sensitivity/result.json](https://remilab.cnu.ac.kr/share/7c02ad43c580/patch-sensitivity/result.json)
- [Descend through FDTD to a closed-form optimum](https://remilab.ai/rfx/markdown/showcase/descent-to-optimum.md): catalog entry `descent-to-optimum` in [showcase.json](https://remilab.ai/rfx/showcase/showcase.json); [ar-coating/result.json](https://remilab.cnu.ac.kr/share/7c02ad43c580/ar-coating/result.json)
- [The forward model, next to openEMS](https://remilab.ai/rfx/markdown/showcase/forward-checks.md): catalog entry `forward-checks` in [showcase.json](https://remilab.ai/rfx/showcase/showcase.json); [forward-patch/result.json](https://remilab.cnu.ac.kr/share/7c02ad43c580/forward-patch/result.json), [forward-notch/result.json](https://remilab.cnu.ac.kr/share/7c02ad43c580/forward-notch/result.json)

## Manual and examples

- [Automation](https://remilab.ai/rfx/markdown/api/functions.md): Derived setup helpers for mesh, domain, and frequency-range configuration.
- [Generated API Reference](https://remilab.ai/rfx/markdown/api/generated.md): Signatures and docstrings generated from this documentation version's Python source.
- [Geometry and Materials](https://remilab.ai/rfx/markdown/api/geometry-materials.md): Documented shape constructors and material registration for rfx.
- [API Reference](https://remilab.ai/rfx/markdown/api.md): Documented rfx API pages and configuration limits.
- [Documentation for Agents and Scripts](https://remilab.ai/rfx/markdown/api/machine-readable.md): Versioned Markdown, signatures, support contracts and source provenance for programmatic readers.
- [Results and Observables](https://remilab.ai/rfx/markdown/api/results.md): What the public rfx run result contains, and how to choose observables.
- [Simulation](https://remilab.ai/rfx/markdown/api/simulation.md): Constructor, run loop, and orchestration entry points for the curated rfx API.
- [Sources and Ports](https://remilab.ai/rfx/markdown/api/sources-ports.md): Current source, waveform, and port entry points for rfx.
- [Check the model on the grid](https://remilab.ai/rfx/markdown/check/model-on-grid.md): What the grid built from your drawing, and how preflight reports a difference.
- [Refused inputs](https://remilab.ai/rfx/markdown/check/refusals.md): How rfx refuses an input it would not solve, and where to find the way through.
- [Design regions](https://remilab.ai/rfx/markdown/design/design-regions.md): The parts of a model a gradient can change.
- [Autodiff and Adjoint Background](https://remilab.ai/rfx/markdown/design/gradients.md): How rfx computes design gradients with JAX reverse-mode autodiff, how that relates to the adjoint method, and how to check a gradient before you optimize with it.
- [Inverse Design](https://remilab.ai/rfx/markdown/design/optimization.md): Gradient-based design through the FDTD solver: the optimize() design-region driver, which objectives run inside the gradient loop, the manual jax.grad loop, and lumped-component value design.
- [Parametric Sweeps](https://remilab.ai/rfx/markdown/design/sweeps.md): Sweep geometry and material parameters in rfx: one-parameter sweeps, Cartesian grids, batched material sweeps with jax.vmap, and resumable sweeps with a manifest.
- [The accuracy bar and status words](https://remilab.ai/rfx/markdown/evidence/accuracy-bar.md): What validated, diagnostic, provisional, planned and refused mean on these pages.
- [Checking a gradient](https://remilab.ai/rfx/markdown/evidence/gradients.md): Whether a gradient is converged in the simulation time and agrees with finite differences.
- [Tutorial: Convergence Study](https://remilab.ai/rfx/markdown/evidence/mesh-convergence.md): Step-by-step mesh convergence analysis for rfx FDTD simulations.
- [Is the run long enough?](https://remilab.ai/rfx/markdown/evidence/simulation-time.md): The per-frequency decay check and tail extrapolation.
- [Your First Patch Antenna](https://remilab.ai/rfx/markdown/examples/first-patch.md): Build a 2.4 GHz rectangular patch on FR4 with a graded mesh, read what preflight tells you, and learn what a trustworthy resonance or return-loss result still needs.
- [Examples](https://remilab.ai/rfx/markdown/examples.md): The ordered learning path of runnable scripts shipped in examples/, what each one teaches, and which ports and boundaries it uses.
- [Tutorial: Patch Antenna Design](https://remilab.ai/rfx/markdown/examples/patch-antenna.md): The workflow from a patch model that runs to a resonance, return loss and pattern you can report, and how to iterate the design with sweeps or gradients.
- [Steer a beam with a dielectric cover](https://remilab.ai/rfx/markdown/gallery/beam-steering.md): Watch a dielectric pattern and its directional radiation response change during a recorded design history.
- [Let a pulse leave, or reflect it back](https://remilab.ai/rfx/markdown/gallery/boundary-reflection.md): Actual field snapshots compare a pulsed open CPML domain with a closed PEC box, using the same source and a shared color scale.
- [A pulse leaves a standing wave](https://remilab.ai/rfx/markdown/gallery/cavity-standing-wave.md): Watch real time-domain electric-field samples ring inside a closed rectangular PEC cavity after the drive ends.
- [Watch a pulse meet a dielectric](https://remilab.ai/rfx/markdown/gallery/dielectric-interface.md): A vacuum reference and a dielectric half-space reveal how a real pulsed electric field changes at a material interface.
- [Visual archive](https://remilab.ai/rfx/markdown/gallery.md): Watch electromagnetic fields, explore RF components and follow differentiable design histories.
- [Tune a microstrip notch](https://remilab.ai/rfx/markdown/gallery/microstrip-notch.md): Connect an open-stub length to a design trajectory and inspect its frequency-domain electric field.
- [Dielectric slab (normal incidence)](https://remilab.ai/rfx/markdown/gallery/multilayer_fresnel.md): Normal-incidence reflection and transmission of a lossless dielectric slab in free space — rfx FDTD against the exact transfer-matrix (Fresnel) solution to about 1%.
- [Patch Antenna Diagnostics](https://remilab.ai/rfx/markdown/gallery/patch_antenna.md): Plots and AD/FD data from a patch model that cannot support RF resonance, return-loss, or convergence conclusions.
- [The visual manual](https://remilab.ai/rfx/markdown/gallery/visual-manual.md): Read electromagnetic simulations through their geometry, field evolution and measured response.
- [A dielectric taper for a guided wave](https://remilab.ai/rfx/markdown/gallery/waveguide-taper.md): Watch a material profile, reflection spectrum and sensitivity change together during a recorded optimization.
- [Hollow rectangular waveguide (WR-90, TE10)](https://remilab.ai/rfx/markdown/gallery/waveguide_wr90.md): A TE10 mode propagates down an empty WR-90 guide above cutoff — |S11|/|S21| match the exact matched-guide answer, with a jax.grad sensitivity of |S21| to the dielectric fill validated against finite differences.
- [ADI Solver (Experimental)](https://remilab.ai/rfx/markdown/guide/adi-solver.md): Experimental ADI-FDTD for closed, homogeneous cavities: the timestep trade and what it refuses.
- [Simulation API](https://remilab.ai/rfx/markdown/guide/api-reference.md): A one-page map of the main rfx methods and result objects, with links to the full API reference.
- [Benchmarks](https://remilab.ai/rfx/markdown/guide/benchmarks.md): The cross-solver comparisons that ship with rfx: what each one checks, against which reference, what it shows, and how to reproduce it.
- [Your first run](https://remilab.ai/rfx/markdown/guide/first-run.md): Send a pulse into a small closed box and read one field probe using the repository's install check.
- [Gradient Behavior in rfx](https://remilab.ai/rfx/markdown/guide/gradient-behavior.md): Where rfx gradients are reliable, where they are noisy or meaningless, and three checks to run before you optimize: finite differences, loss magnitude, and record length.
- [Learn rfx](https://remilab.ai/rfx/markdown/guide.md): A visual route from the first electromagnetic field to measured RF responses and design.
- [Cross-Validation and Accuracy](https://remilab.ai/rfx/markdown/guide/validation.md): How to know an rfx result is right: what rfx checks for you, what you must check yourself, and where the evidence lives.
- [Waveguide Ports](https://remilab.ai/rfx/markdown/guide/waveguide-ports.md): 
- [rfx](https://remilab.ai/rfx/markdown/index.md): An open-source 3-D FDTD simulator for RF and microwave engineering, written in JAX, that returns the gradient of S-parameters, radiation patterns and fields with respect to every cell of a design region.
- [Far-Field & Radar Cross Section](https://remilab.ai/rfx/markdown/measure/far-field-and-rcs.md): 
- [Visualization & Result Analysis](https://remilab.ai/rfx/markdown/measure/plots-and-export.md): 
- [Probes and fields](https://remilab.ai/rfx/markdown/measure/probes-and-fields.md): Probes, time series, frequency-domain planes and flux monitors.
- [Resonances](https://remilab.ai/rfx/markdown/measure/resonances.md): Resonant frequencies and Q from a matrix pencil fit of a probe signal.
- [Probes and S-Parameters](https://remilab.ai/rfx/markdown/measure/s-parameters.md): Extract field data with point, vector, and DFT-plane probes; compute S-parameters per port family; and pull resonances via harmonic inversion.
- [Boundaries](https://remilab.ai/rfx/markdown/model/boundaries.md): Absorbing, electric, magnetic and periodic faces, and the rules ports and plane waves put on them.
- [Conductors](https://remilab.ai/rfx/markdown/model/conductors.md): Volumes, sheets and wires, lossy films, and how a conductor is placed on the grid.
- [Non-Uniform Mesh](https://remilab.ai/rfx/markdown/model/domain-mesh.md): Graded-z mesh setup and limits for thin layered RF structures.
- [Materials and Geometry](https://remilab.ai/rfx/markdown/model/materials.md): Library and custom materials, dispersive poles, CSG shapes, PEC handling, and thin conductors in rfx.
- [Sources and Ports](https://remilab.ai/rfx/markdown/model/ports.md): rfx source and port primitives: waveforms, point and polarized sources, lumped/wire/microstrip/waveguide ports, TFSF plane waves, and how each feeds S-parameter extraction.
- [Sources](https://remilab.ai/rfx/markdown/model/sources.md): Point sources, plane waves and waveforms.
- [Changelog](https://remilab.ai/rfx/markdown/project/changelog.md): What changed for users in each rfx release, and what is coming in 2.0.
- [Citing rfx](https://remilab.ai/rfx/markdown/project/citation.md): How to cite rfx.
- [Contributing to rfx](https://remilab.ai/rfx/markdown/project/contributing.md): 
- [Reduce Memory Use](https://remilab.ai/rfx/markdown/run/memory-and-speed.md): Estimate and reduce reverse-mode AD memory in rfx: plan a checkpointing option for a budget, use design boxes and graded meshes, inspect what JAX saves, and check a compiled executable.
- [Multi-device runs](https://remilab.ai/rfx/markdown/run/multi-device.md): Splitting one model across several devices.
- [Run and forward](https://remilab.ai/rfx/markdown/run/run-and-forward.md): Running a model, the number of time steps, precision and the differentiable run.
- [Descend through FDTD to a closed-form optimum](https://remilab.ai/rfx/markdown/showcase/descent-to-optimum.md): Adam, driven by gradients through the FDTD solve, finds the layer permittivities of a three-layer anti-reflection coating within 1.1 % of the transfer-matrix optimum.
- [The forward model, next to openEMS](https://remilab.ai/rfx/markdown/showcase/forward-checks.md): The input impedance of the RT/Duroid 5880 patch and |S21| of a microstrip open-stub notch filter, solved by rfx and openEMS on the same boards.
- [What does a gradient cost?](https://remilab.ai/rfx/markdown/showcase/gradient-cost.md): Wall time and memory of the value and gradient against a forward run, for design regions of 12,400 to 43,008 cells on one GPU.
- [Showcase](https://remilab.ai/rfx/markdown/showcase.md): Results computed with the current rfx code, each with an independent check: a patch antenna's sensitivity map, the cost of a gradient, gradient descent to a closed-form optimum, and the forward model next to openEMS.
- [Which cells move a patch antenna's match?](https://remilab.ai/rfx/markdown/showcase/sensitivity-map.md): One reverse pass through a 3-D FDTD solve gives the derivative of |S11|² with respect to the permittivity of each of 20,592 substrate cells of a probe-fed patch.
- [Migration Guide](https://remilab.ai/rfx/markdown/start/coming-from-other-solvers.md): 
- [Core Concepts](https://remilab.ai/rfx/markdown/start/concepts.md): The mental model behind every rfx simulation: cells and time steps, boundaries, materials, the three kinds of conductor, sources versus ports, observables, and how to know a run is finished.
- [Quick Start](https://remilab.ai/rfx/markdown/start/first-simulation.md): Build, check, run and read your first rfx simulation in about ten lines of Python.
- [Installation](https://remilab.ai/rfx/markdown/start/install.md): Install rfx on CPU or GPU, check the install, and set up a development checkout.
- [rfx terms and their field equivalents](https://remilab.ai/rfx/markdown/start/terms.md): The names rfx uses, what each means, and the nearest term in the FDTD and microwave literature.
- [Upgrading to 2.0](https://remilab.ai/rfx/markdown/start/upgrading.md): What changes in your results and your scripts from rfx 1.x to 2.0.
- [Support Boundaries](https://remilab.ai/rfx/markdown/support.md): Current public support boundaries for rfx.
- [Known limitations](https://remilab.ai/rfx/markdown/support/known-limitations.md): Defects and limits inside the supported scope.
- [Cross-Solver Validation](https://remilab.ai/rfx/markdown/validation/cross-solver.md): How to run an rfx cross-solver comparison, read its result, and cite it.
- [Validation](https://remilab.ai/rfx/markdown/validation.md): Where to find how rfx is checked, which setup to start from, and how to reproduce a comparison.
- [Recommended Configuration](https://remilab.ai/rfx/markdown/validation/recommended-configuration.md): Where to start, and the extra limits each S-parameter calculator and non-default mesh carries.