HFSS15: Magnetic Bias Sources

When you create a ferrite material, you must define the net internal field that biases the ferrite by assigning a magnetic bias source. The bias field aligns the magnetic dipoles in the ferrite, producing a non-zero magnetic moment. In HFSS, a ferrite’s permeability tensor is a direct result of an applied static magnetic bias field. The static field causes the tensor to assume an hermitian form, with cross coupling terms between field components perpendicular to the bias.

When the applied bias field is assumed to be uniform, you will specify net internal bias field as well as the tensor coordinate system through a rotation from the global coordinate system. When the applied bias field is non-uniform, neither specified coordinate system rotations nor specified bias are allowed. The permeability tensor’s local coordinate system and bias field are calculated on a tetrahedron by tetrahedron basis, both of which are determined by the calculated static solution. HFSS references the static solution project as the source of the non-uniform magnetostatic field information during solution generation.

Multiple uniform bias excitations may be included in a design, but only non-uniform bias is allowed. In addition, a design cannot contain a bias excitation of both types. If only one excitation is included in a design, its type can be changed from uniform to non-uniform, and visa versa.