Circularly polarized traveling wave cavity for ferrite tensor permeability measurements

A circularly polarized travelling wave cavity (abbreviated cp-twc) is described for use in measuring the components of the tensor permeability of ferrites. The cp-twc is a ring of waveguide all of which is rectangular except for a section of cylindrical waveguide in which the rf field is circularly polarized (cp). The ferrite sample, centered axially in this cylindrical section, is a rod 0.050 inch in diameter and 1.0 inch in length. A dc magnetic field is applied longitudinally to the rod and as the field is varied, the transmission through the cavity and the resonant frequency of the cavity change. By measuring these changes for both positive and negative cp-rf fields the components of the tensor permeability are obtained.