Impedance Boundary Condition

Impedance Boundary Condition

is used at boundaries where the field is known to penetrate only a short distance outside the boundary. This penetration is approximated by a boundary condition to avoid the need to include another domain in the model. Although the equation is identical to the one in the low-reflecting boundary condition, it has a different interpretation. The material properties are for the domain outside the boundary and not inside, as for low-reflecting boundaries. A requirement for this boundary condition to be a valid approximation is that the magnitude of the complex refractive index

where μ1 and ε1 are the material properties of the inner domain, is large; that is, | N | >> 1.

The source electric field Es can be used to specify a source surface current on the boundary.

The Surface Roughness subnode is available from the context menu (right-click the parent node) or from the toolbar, menu.

Figure 4-4: The impedance boundary condition is used on exterior boundaries representing the surface of a lossy domain. The shaded (lossy) region is not part of the model. The effective induced image currents are of reduced magnitude due to losses. Any current flowing into the boundary is perfectly balanced by induced surface currents as for the perfect electric conductor boundary condition. The tangential electric field is generally small but nonzero at the boundary.

Impedance Boundary Condition

Select an — (the default), , , , , , or . See the Wave Equation, Electric node, Electric Displacement Field section, for all settings.

Source electric field

To display this section, click the button (

) and select in the dialog box.

Enter a Es (SI unit: V/m). The default is 0 V/m.


	Coaxial to Waveguide Coupling: Application Library path RF_Module/Transmission_Lines_and_Waveguides/coaxial_waveguide_coupling Computing Q-Factors and Resonant Frequencies of Cavity Resonators: Application Library path RF_Module/Verification_Examples/cavity_resonators