Abstract :
Normally, the magnetic properties of ferrites, such as permeability and losses, are determined by measurements on ring samples. Extruded products, however, are mostly anisotropic, so that data obtained from rings cut out of the rods are not representative of the properties of the extrusions. The paper deals with the measurement of the initial permeability of ferrite rods at high frequencies (about 300kc/s). Rods with rectangular as well as circular cross-sections have been tested. In all cases, the initial permeability is determined by measuring the amplitude permeability in terms of peak magnetising force and peak magnetic flux density at low flux densities. The methods investigated are (a) measurement using a tangential-field coil, (b) an a.c. version of the Iliovici permeameter and (c) measurements by means of a magnetic potentiometer.
