- Electric and magnetic point dipoles allow for easy and computationally efficient incorporation of electromagnetic sources in electromagnetic wave propagation models. Many antennas can be approximated by one or more point dipoles.
- A Transition boundary condition for metallic layers of arbitrary thickness provides accurate modeling of geometrically thin metal sheets without having to mesh the thickness. This substantially helps to reduce the number of elements and the problem size. The layer can be of arbitrary electrical thickness (measured relative to the skin depth) and have a more or less pronounced discontinuity in the tangential electric field.
- A new variational S-parameter formulation supports multimode ports and numerical hybrid-mode ports. This allows for accurate modeling of dielectrically loaded waveguides and optical waveguides.
- Port sweep for frequency-dependent S-parameter calculations in the graphical user interface makes it easy to compute full S-parameter matrices. These can be exported in the Touchstone file format.
- The new Electrical Circuit physics interface with predefined passive and active components is integrated with other physics interfaces in the RF Module via the port and lumped port boundary conditions. It is now possible to build electrical circuits directly in the Model Builder. SPICE netlists are imported and translated into native and editable COMSOL circuit elements in the Model Builder.
All backward compatibility issues are planned to be solved for version 4.0a unless explicitly stated.
Change in Dependent Variables
Version 4.0 has a comprehensive set of electromagnetic wave propagation formulations based on the electric field that covers all modeling situations.
However, it is no longer possible to solve for the magnetic field H as a dependent variable.
Models saved in version 3.5a that are based on an H formulation are translated to the new E formulation but need to be solved again to update the solution in version 4.0.
Cylindrical PMLs in 3D are not yet implemented. Possible workarounds are to use Cartesian or spherical PMLs instead.
Far fields are not automatically read in when importing a 3.5a model into version 4.0. The workaround is to manually add a Far Field Calculation node.
Pair Boundary Conditions
Pair boundary conditions are not yet implemented, except for continuity.
This means that the assembly port boundary condition is not supported in version 4.0. In version 4.0a, this will be available as a new type of slit-based boundary condition, which does not require the use of assemblies.