Interactions between drive coils and ferrite sheets in bubble memory packages

Sheets of ferrite or other permeable materials situated very close to drive coils are expected to affect the field distributions within the coils and the inductances of the coils. A theoretical study has been made of a system consisting of a flat rectangular coil with sheets in contact with its flat faces, including the effects of the shapes of the sheets and their permeability and of an angle of tilt between the coil axis and the sheets. The results are compared with experimental results.