openEMS is a free and open electromagnetic field solver using the FDTD method that supports cartesian and cylindrical coordinates. Matlab or Octave are used as an easy and flexible scripting interface.


Thorsten Liebig1, Andreas Rennings1, Sebastian Held1, Daniel Erni1




Stable release v0.0.34 (GNU GPL v3 or later)

OpenEMS is a free and open source FDTD solver written in C++. OpenEMS supports cylindrical coordinates and is specifically developed for MRI applications. An extensive Matlab (or Octave) interface is used to define the FDTD options. The geometry used for the FDTD simulations is handled by the CSXCAD library which is part of the openEMS project.


  • Efficient EC-FDTD method in full 3D cartesian coordinates (x,y,z)
  • Efficient EC-FDTD method in full 3D cylindrical coordinates (ρ,φz)
  • Supports virtual family voxel models
  • Fully graded mesh
  • Multi-threading, SIMD (SSE) and MPI support for high speed parallel FDTD
  • Simple engine extensions API to easily introduce new features to the FDTD algorithm
  • Matlab-Interface
  • Absorbing boundary conditions (MUR, PML)
  • Coordinate dependent material definitions
  • Coordinate dependent excitation definitions (e.g. mode-profiles)
  • Dispersive material (Drude/Lorentz/Debye type)
  • Field dumps in time and frequency domain as vtk or hdf5 file format
  • Flexible post-processing routines (mostly in Matlab)
  • Subgrids to reduce simulation time in cylindrical coordinates
  • Remote simulations using SSH (Linux only)


Liebig, A. Rennings, S. Held, and D. Erni, “openEMS – A free and open source equivalent-circuit (EC) FDTD simulation platform supporting cylindrical coordinates suitable for the analysis of traveling wave MRI applications,” International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, online, DOI:10.1002/jnm.1875, Dec. 10, 2012.

Liebig, A. Rennings, and D. Erni, “openEMS – A free and open source FDTD software package supporting Cartesian and cylindrical coordinates ideally suited for MRI applications,” Magnetic Resonance in Physics, Biology and Medicine (MAGMA), vol. 25, no. suppl 1, pp. 627-628, Oct. 2012, special supplement on Europ. Soc. for Magn. Reson. in Med. and Biol. 29th Annual Sci. Meeting (ESMRMB 2012), Oct. 4-6, Lisbon, Portugal, paper 857 (demo and poster), 2012.

Liebig, A. Rennings, and D. Erni, “openEMS – A Free and Open Source Cartesian and Cylindrical EC-FDTD Simulation Platform Supporting Multi-Pole Drude/Lorentz Dispersive Material Models for Plasmonic Nanostructures,” 8th Workshop on Numerical Methods for Optical Nano Structures (organized by OptETH and the Fred Tischer Lecture Series), July 2-4, ETH Zurich, Session on Metamaterials, Periodic Structures, and Numerical Methods I, Switzerland, 2012.

Liebig, D. Erni, A. Rennings, N. H. L. Koster, and J. Fröhlich, “MetaBore – A fully adaptive RF field control scheme based on conformal metamaterial ring antennas for high-field traveling-wave MRI,” Magnetic Resonance in Physics, Biology and Medecine (MAGMA), vol. 24, no. suppl 1, pp. 37-38, special supplement on the Europ. Soc. for Magn. Reson. in Med. and Biol. 28th Annual Sci. Meeting (ESMRMB 2011), paper 49 (talk and poster), pp. 22, Oct. 6-8, Leipzig, Germany, 2011.

Erni, T. Liebig, A. Rennings, N. H. L. Koster, and J. Fröhlich, “Highly adaptive RF excitation scheme based on conformal resonant CRLH metamaterial ring antennas for 7-Tesla traveling-wave magnetic resonance imaging,” 33th Annual Intern. Conf. of the IEEE Engineering in Medicine and Biology Soc. (IEEE EMBS 2011), Aug. 30 – Sept. 3, Boston, MA, USA, pp. 554-558, 2011.


1General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen and GENIDE – Center for Nanointegration Duisburg-Essen, Duisburg, Germany


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