Transition Boundary Condition
The Transition Boundary Condition is used on interior boundaries to model a sheet of a medium that should be geometrically thin but does not have to be electrically thin. It represents a discontinuity in the tangential electric field. Mathematically it is described by a relation between the electric field discontinuity and the induced surface current density:
where indices 1 and 2 refer to the different sides of the layer. This feature is not available with the Electromagnetic Waves, Transient interface.
The Transition Boundary Condition is based on the assumption that the wave propagates in the normal direction in the thin layer. Thus, the wave could be incident in the normal direction or the wave could be refracted to propagate in a direction close to the normal direction. The latter condition is fulfilled for a good conductor.
The thickness of the layer should also be less than the radius of curvature for the boundary and the material properties in the thin layer are assumed to be isotropic.
A consequence of the normal direction propagation assumption is that the Transition Boundary Condition is not compatible with mode analysis, as for mode analysis it is assumed that the wave predominantly propagates in the out-of-plane direction whereas the normal to the boundary is in an in-plane direction.
The Surface Roughness and Surface Current Density subnodes are available from the context menu (right-click the parent node) or from the Physics toolbar, Attributes menu.
Transition Boundary Condition
Select an Electric displacement field model — Relative permittivity (the default), Refractive index, Loss tangent, loss angle, Loss tangent, dissipation factor, Dielectric loss, Drude–Lorentz dispersion model, or Debye dispersion model. See the Wave Equation, Electric node, Electric Displacement Field section, for all settings. However, notice that only isotropic (scalar) material parameters are supported for this boundary condition.
Select a Type — Electrically thin layer, Electrically thick layer, or Electrically very thin layer. The Electrically thick layer option decouples the two domains adjacent to the boundary. This setting is suitable, for example, when the thickness exceeds three times the skin depth. If the thickness is much smaller than the skin depth, select Electrically very thin layer. For both the Electrically thin layer and Electrically very thin layer options, specify a Thickness d (SI unit: m). The default is 0.01 m.
Resonance Constraint
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog. Select the Activate resonance constraint checkbox to apply the constraint to address resonance conditions, for lossless materials when the entered Thickness d is an integer number of half wavelengths. It is cleared by default.
Skin Depth Calculator
Select a Defined by option — Electric conductivity (default) or Resistivity. Enter a Electric conductivity σ (SI unit: S/m) or Resistivity ρ (SI unit: Ω·m), Relative permittivity εr, Relative permeability μr of the material to be evaluated, and Frequency f0 (SI unit: Hz). Then click the Compute Skin Depth button () to compute the skin depth for the particular material specified by the above input values. The result is displayed in the settings window below the Compute Skin Depth button.