Modern Magnetic Ferrites and Their Engineering Applications

Ferrites and their applications constitute a rapidly developing field. This paper reviews the present status of the development, properties, and applications of ferrites and their significance to modern engineering. Magnetic ferrites were developed from a "new look" at lodestone, the oldest magnetic material known to man. Proper control of composition and heat treatment yields ceramic type bodies with high permeabilities, which were formerly obtained only in metals. This material has brought the physicist new insight into the mechanisms of magnetism, and has given the design engineer a variety of new materials with unprecedented combinations of properties. The unique characteristics of ferrites are bringing about revolutionary design techniques in inductors and transformers for use at carrier, radio, and video frequencies, and have made possible an important new family of nonreciprocal circuit elements in microwave applications.