Boundary Type

E-Field Behavior

Used to model...

Default Boundary Conditions (Natural and Neumann)

Field behaves as follows:

• Natural boundaries - The normal component of J and the 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; its normal components are zero.
• Odd Symmetry (Flux Normal) - E and J vectors are normal to the boundary; its 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, equipotential lines can cross this type of boundary. In general, they are neither tangent nor perpendicular to the balloon boundary.

Matching

(Independent and Dependent)

The E-field on the dependent boundary is forced to match the magnitude of the E-field on the independent boundary if the plus sign is used. If the minus sign is used, the field on the dependent boundary will oscillate with opposite phase angle (180 degrees phase shift).

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