A survey of the theory and applications of ferrites at microwave frequencies

The paper opens with a brief review of gyromagnetic media in general, followed by a more detailed description of the microwave behaviour of a ferromagnetic medium, of which ferrites form a suitable class of material. The general physical properties of ferrites are outlined briefly, together with a description of several of the mechanisms to account for the dispersion which occurs in their r.f. permeability. The propagation of an electromagnetic wave through an infinite ferrite medium is considered. The properties of different guided systems containing ferrites are then studied. The behaviour of various ferrite waveguide structures is described and their applications are suggested. Most of the data quoted are from published papers, but in a few instances some unpublished work of the authors has been included for completeness. An extensive bibliography completes the survey.