HFSS15: Calculating the E-Field on the Slave Boundary

The E-field on the slave boundary is forced to match the E-field on the master boundary. The magnitude of the E-field on both boundaries is the same; however, the fields may be out of phase with each other.

The function relating the electric field on the slave boundary, E_S, to the electric field on the master boundary, E_M, depends on the type of problem you are solving. For example, consider an infinite array simulation for a rectangular array. If the array excited to radiate in the direction (q, f) in spherical coordinates. The fields above the array experience a phase delay of

(1)

where

•  is the unit vector in the direction of scan.

• v is the vector from the slave boundary to the master boundary.

To simulate this in the finite element solution, HFSS incorporates phase shifts in the relation between the matching boundaries. That is, the electric field values on the master boundary will be related to the electric field values on the corresponding points on the slave boundary. This equation would be the following:

(2)

HFSS gives you the option of entering the scan angles, f and q, when relating E_S to E_M. The phase delay is calculated from the scan angles. However, if you know the phase delay, you may enter that directly.