Boundary Type

E-Field Behavior

Used to model...

Default Boundary Conditions (Natural and Neumann)

Field behaves as follows:

• Natural boundaries — Normal component of J and tangential component of E are continuous across discontinuity surfaces. No special conditions are imposed.
• Neumann boundaries — E and J vectors are tangential to the boundary. Flux cannot cross a Neumann boundary.

Object interfaces are initially set to natural boundaries; outer boundaries are initially set to Neumann boundaries.

Symmetry

Field behaves as follows:

• Even Symmetry (Flux Tangential) — E and J vectors are tangential to the boundary; their normal components are zero.
• Odd Symmetry (Flux Normal) — E and J vectors are normal to the boundary; their tangential components are zero.

Planes of geometric and electrical symmetry.

Balloon

Balloon boundaries model the region outside the drawing space as being nearly “infinitely” large — effectively isolating the model from other voltage sources.

Electrically insulated structures.

Resistance

A resistance boundary models a very thin layer of resistive material (such as that caused by deposits, coatings or oxidation on a metallic surface) on a conductor at a known potential.

Use this boundary condition when the resistive layer’s thickness is much smaller than the other dimensions of the model.

Matching
(Independent and Dependent)

The E-field on the dependent boundary is forced to match the magnitude and direction (or the negative of the direction) of the E-field on the independent boundary.

Planes of symmetry in periodic structures where E is oblique to the boundary.