General Applicability of the Technique

Full coupling between MoM and FEM regions.

The FEM is applicable to the modelling of electrically large or inhomogeneous dielectric bodies, which are not efficiently solvable with FEKO's extensions to the MoM. The FEM is a volume meshing technique that employs tetrahedra to accurately mesh arbitrarily shaped volumes where the dielectric properties may vary between neighbouring tetrahedra. 

Technical Foundation (Hybrid FEM/MoM)

The FEM/MoM hybridisation features full coupling between metallic wires and surfaces in the MoM region and heterogeneous dielectric bodies in the FEM region. The MoM part of the solution is calculated first, which results in equivalent magnetic and electric currents that form the radiation boundary of the FEM region. This hybrid technique makes use of the strengths of both the MoM and the FEM in the following ways:

• The MoM is used for the efficient modelling of open boundary radiating structures where no 3D space discretisation is required.
• The FEM is used for the efficient modelling of inhomogeneous dielectric bodies in term of field distributions inside the volume.
  

A parallelised FEM/MoM hybrid is available from FEKO 5.4 and provides two significant solution features:

• All solution phases of the FEM/MoM hybrid have been parallelized and as such much faster solution times are achievable.
  
• Electrically larger or dielectrically more complex FEM/MoM problems can now be solved on less expensive computing platforms.  This is achieved through the use of distributed memory computing clusters, rather than shared memory platforms.

Typical Application of the FEM

Typical applications of the FEM/MoM hybrid method include radiation hazard investigations where humans interact with RF equipment, the modelling of waveguide filters with dielectric blocks in the filter and the modelling of microstrip patches on finite substrates.

10g cube localised SAR peak in a FEM phantom wearing a metallic stab-proof jacket and a TETRA personal radio.