HFSS15: Impedance Boundaries

In HFSS, impedance boundaries represent surfaces of known impedance. The behavior of the field at the surface and the losses generated by the currents flowing on the surface are computed using analytical formulas; HFSS does not actually simulate any fields inside the resistor.

Similar to finite conductivity boundaries, the following condition applies at impedance boundaries:

(1)

where

•  is the is the unit vector that is normal to the surface.

• E_tan is the component of the E-field that is tangential to the surface.

• H_tan is the component of the H-field that is tangential to the surface.

• Z_s is the surface impedance of the boundary, Rs + jXs, where

• Rs is the resistance in ohms/square.

• Xs is the reactance in ohms/square.

For example, assume that a structure contains two dielectrics separated by a thin-film resistor. This resistor could be represented by an impedance boundary at the surface between the two objects.