rfx Documentation

rfx is a JAX-based differentiable FDTD simulator for RF and microwave engineering. This index tracks the v1.4.0 release surface and highlights selected workflow-hardening and validation updates already merged on main.

Recent highlights

v1.4.0 optimization workflows: waveguide / Floquet ports now work inside differentiable forward() and optimize() loops.
v1.4.0 data products: geometry JSON, experiment reports, simulation datasets, optimisation trajectories, and richer export helpers.
Advanced solver coverage: multi-GPU FDTD, JAX far-field evaluation, experimental ADI 2-D / 3-D paths, and SBP-SAT subgridding.
Current main adds stronger workflow safety via sim.preflight(), broader cross-validation coverage, and newer primitives such as PolylineWire.

How this guide is organized

The sidebar already groups pages by job-to-be-done. The table below gives the same structure in one place so you can jump directly to the right section.

Getting Started

Guide	Description
Installation	Python/JAX install, GPU notes, dev setup
Quick Start	First simulation with the current stable high-level API
Your First Patch Antenna	First end-to-end success path for a practical RF structure

Modeling & Setup

Guide	Description
Simulation API	`Simulation`, `Result`, materials, sources, probes, ports, and NTFF helpers
Materials & Geometry	Material library, Debye/Lorentz models, CSG shapes, and PCB stackup basics
Sources & Ports	Soft sources, lumped/wire ports, waveguide ports, and Floquet workflows
Probes & S-Parameters	DFT probes, S-matrix extraction, Harminv, de-embedding, and exports
Non-Uniform Mesh	`dz_profile`, `auto_configure()`, thin-substrate workflow
Waveguide Ports	Modal waveguide excitation and calibrated multi-mode S-matrix extraction
Floquet Ports	Bloch-periodic unit-cell workflows for phased and periodic structures

Analysis & Validation

Guide	Description
Validation	Published RF benchmarks, cross-solver checks, and workflow-validation guidance
Convergence Study	Mesh-refinement analysis and accuracy verification workflow
Far-Field & RCS	NTFF radiation patterns and scattering workflows
Antenna Metrics	Gain, efficiency, beamwidth, bandwidth, and front-to-back ratio
Visualization & Analysis	Plots, exports, post-processing, and result interpretation
Solver Comparison	Feature and workflow comparison vs. Meep and OpenEMS

Design & Optimization

Guide	Description
Inverse Design	Gradient-based optimization, proxy objectives, and NTFF-aware advanced workflows
Topology Optimization	Density-based inverse design with filtering and projection
Parametric Sweeps	Sequential sweeps and `jax.vmap` batch evaluation
Material Fitting	CSV import, Debye/Lorentz fitting, and differentiable fitting workflows
Patch Antenna Design	Full rectangular patch design workflow
Microstrip Filter Design	Coupled-line filter workflow with two-port analysis

Advanced & Research Methods

Guide	Description
Advanced Features	Multi-GPU, material fitting, mixed precision, nonlinear materials, and research examples
Conformal PEC	Dey-Mittra method for curved PEC conductors
SBP-SAT Subgridding	Local mesh refinement with JIT performance
Gradient Behavior	Where gradients are strong, weak, or noisy
Geometry & Limitations	Supported workflows, strengths, and current trade-offs

Start Here

If you’re new to rfx, start here:

Installation
Quick Start
Simulation API
Sources & Ports
Non-Uniform Mesh
Validation
Advanced Features once you want distributed runs, proxy objectives, or research-style workflows

Project & maintainer guides

Guide	Description
Migration Guide	Mapping Meep/OpenEMS workflows into rfx
Changelog	Release notes and current-main capability updates
Contributing	Maintainer workflow, testing, linting, and coding conventions

API Reference

Generate API documentation locally:

pip install pdoc
pdoc rfx -o docs/api

Then open docs/api/index.html in your browser.

Quick Links

GitHub: bk-squared/rfx
Public docs snapshot: remilab.ai/rfx
Top-level API exports: rfx.__init__
Package metadata: pyproject.toml
Advanced example bundle: examples/50_advanced/