Basic Properties of Polycrystalline Ferrites Ferrite materials are magnetic oxides, known as ferrimagnetic materials, which are characterized by high magnetic permeability values and insulating behavior over a wide frequency range. Their high electrical resistivity make low-loss ferrimagnets the ideal basis for passive microwave components operating over a wide range of frequencies, from 1 to 100 GHz. They are needed in devices where nonreciprocal behavior is expected, or to strengthen the interaction between a device and the electromagnetic signal. Depending on the applications, either hard or soft ferrites are used. Ferrites have the following main physical properties