FDTD, FEM or MoM? An EM Solver Guide

Open the guide → · Source on GitHub

It runs in your browser. There’s nothing to install.

Overview

The guide explains how FDTD, FEM and MoM work and when to use each one.

• Devices in 3D: 20 devices, from an on-chip spiral to a ship, each with the real mesh made with Gmsh: FEM tetrahedra, an FDTD Yee grid and MoM surface triangles.
• How each solver works: step-by-step 3D lessons on the Yee cell, the tetrahedron and the RWG basis function, each with a short quiz.
• Convergence: when is each solver done? Demos include FEM adaptive passes, an FDTD ring-down, the Courant limit and a thin-wire MoM solve of a dipole that runs in the browser.
• Picker: set the size, frequency and problem type, and the method ranking and the first tools to look at update live.
• Tools: data for 62 commercial, open-source and free tools, with paper counts from OpenAlex.
• Companion page, Rays, PO or Hata?: ray tracing, physical optics, diffraction (UTD and knife-edge), SBR and empirical planning models, each with a live demo checked against an exact reference.
• Companion page, Meshing for FEM: Delaunay insertion, advancing front, Ruppert refinement, size fields, 3-D slivers and an adaptive FEM loop on the L-shaped benchmark, from the original papers.

Tech: one self-contained HTML file with three.js. The meshes come from Gmsh scripts in the repo.

The FEM mesh of a 28 GHz antenna in package, with the solver ranking for that device.