# emcvisual

> Free, open-source EMC/EMI tool in the browser: load a PCB (KiCad, IPC-2581 from Altium/Allegro/PADS, ODB++, Eagle) and see its magnetic near field in 3D. Clocks, buck converters, return paths, CISPR 32, openEMS and near-field scans.

emcvisual is a free, open-source (0BSD) web app for electronics and PCB designers. It reads
a board file (KiCad 6 to 10, IPC-2581 from Altium, Allegro/OrCAD or PADS, ODB++, Eagle/Fusion 360), lets you mark the noisy parts of the circuit (clock
and data lines, differential pairs such as USB, the hot loop of a switching regulator / buck
converter, storage inductors) and computes the magnetic and electric near field around the board.
The result is a 3D scene: the field glows above the copper or shows as isosurfaces, field lines
show where the current loops close, a virtual near-field probe shows a spectrum like a spectrum
analyzer, and every source can be heard (tones or a Geiger counter).

It is meant for EMC/EMI work before the lab (EMC pre-compliance), for PCB layout reviews and for
learning: you can see why a slot in a ground plane under a clock line, a layer change from a
GND to a VCC reference plane, or a large switching-regulator loop makes a board louder. Return
currents detour around plane slots and jump through the nearest stitching via or capacitor, and
the detours are drawn in 3D.

How it works: quasi-static Biot-Savart field of straight current filaments, return currents as
mirror images in the reference planes plus geodesic detours through plane copper, shielding by
planes, line and point charges for the electric field, trapezoid line spectra, and a far-field
estimate from the magnetic dipole moment against the selected standard (CISPR 32, CISPR 11, CISPR 14-1, FCC Part 15). For resonances it exports an
openEMS (FDTD) job; the full-wave result loads back as a second field source, and both agree
within about 1 dB in the quasi-static range. It does not predict whether a product passes an EMC
test (no cables or enclosures). Everything runs in the browser; the board file is not uploaded.

More: a near-field scanner chain (3D printer with OctoPrint or USB G-code, tinySA receiver; a
virtual rig for trying it without hardware) with fitting of the source amplitudes to a scan, an
HTML EMC report, live reload when KiCad saves the board, a command-line field check for CI that
flags pull requests making the near field or far-field margin worse, and an experimental VR view.

German: EMV-Simulation für Leiterplatten im Browser. Platine laden (KiCad, IPC-2581, ODB++, Eagle),
Störquellen festlegen, magnetisches Nahfeld in 3D sehen und hören, Rückstrompfade und Grenzwerte prüfen.

Keywords: EMC simulation, EMI simulation, EMC pre-compliance, PCB EMC, PCB EMI, near-field simulation, near-field probe, near-field scanner, magnetic near field, H-field, radiated emissions, CISPR 32, EN 55032, electromagnetic compatibility, electromagnetic interference, KiCad, KiCad EMC, Altium EMC, Eagle PCB EMC, IPC-2581, ODB++, PCB layout review, PCB design, return path, return current, ground plane slot, split ground plane, stitching via, reference plane, buck converter hot loop, switching regulator layout, clock harmonics, signal integrity, differential pair, spectrum analyzer, Biot-Savart, field solver, 3D visualization, WebGL, hardware design, electronics, EMV, EMV-Simulation, elektromagnetische Verträglichkeit, Störaussendung, Leiterplatte, Platinenlayout, Nahfeldsonde, Rückstrompfad, Massefläche, 3D printer near-field scanner, tinySA, OctoPrint, EMC measurement, electric field, openEMS, FDTD, full-wave simulation, open source, open-source EMC tool, free EMC software

## App
- [emcvisual web app](https://tombueng.github.io/emcvisual/): runs in the browser, includes a demo board with typical EMC mistakes

## Docs
- [README](https://github.com/tombueng/emcvisual/blob/main/README.md): overview, features, how to run it locally
- [Stage 1 plan](https://github.com/tombueng/emcvisual/blob/main/docs/stage-1/PLAN.md): goals, milestones, measured numbers
- [Physics model](https://github.com/tombueng/emcvisual/blob/main/docs/stage-1/PHYSICS.md): formulas, assumptions, validity limits, literature, full-wave comparison
- [Architecture](https://github.com/tombueng/emcvisual/blob/main/docs/stage-1/ARCHITECTURE.md): modules, compute and render pipeline
- [User guide](https://github.com/tombueng/emcvisual/blob/main/docs/USER-GUIDE.md): every panel step by step, FAQ, glossary
- [Rule set](https://github.com/tombueng/emcvisual/blob/main/docs/RULES.md): every finding with threshold, origin, confidence and test board
- [Import of other CAD formats](https://github.com/tombueng/emcvisual/blob/main/docs/IMPORT.md): IPC-2581, ODB++, Eagle/Fusion 360
- [EMC mistakes catalogue](https://github.com/tombueng/emcvisual/blob/main/docs/research/EMC-MISTAKES-CATALOGUE.md): 40 layout mistakes with sources

## Optional
- [Roadmap](https://github.com/tombueng/emcvisual/blob/main/docs/ROADMAP.md): stages, measurement hardware, openEMS
- [Field check for CI](https://github.com/tombueng/emcvisual/blob/main/docs/CI-FIELD-CHECK.md): command line, GitHub Actions example
- [openEMS workflow](https://github.com/tombueng/emcvisual/blob/main/tools/openems/README.md): full-wave export, run, import
- [Parts manual for AI agents](https://tombueng.github.io/emcvisual/ai-parts-manual.md): how to fill in source values from datasheets and report missing data
- [License: 0BSD](https://github.com/tombueng/emcvisual/blob/main/LICENSE)
- [Source code](https://github.com/tombueng/emcvisual)