Rod Permeability vs. Rod Length divided by Rod Diameter

(graphic)

This family of curves shows the value of the effective permeability of a ferrite rod as a function of its length to diameter ratio, as well as a function of the material permeability of the rod. It illustrates that generally, a great difference exists between the material permeability and the effective permeability of a rod. It also illustrates how, in some instances, the effective permeability of a rod can be influenced by changing its mechanical dimensions more than by changing it material permeability, while in other cases the reverse is true.