Non-uniform field modeling of ferrite-loaded cavity-backed slot antennas

This communication presents a method that accurately models the non-uniformities of the magnetic field present within the ferrite material that is subjected to an externally applied magnetic field. Two major factors that influence this field are the applied magnetic field and the demagnetizing factor. Most of the formulations reported prior to this work ignored the non-uniformity of the applied magnetic field by assuming that this field is constant and unidirectional everywhere in the cavity. In addition to this, the demagnetizing factor was also assumed to be either of the ballistic or diagonal form. The approach presented here removes both of these approximations by determining the nonuniform field distribution using the finite element method and considering the full tensorial form of the demagnetizing factor. Predictions based on the approach presented here are compared with measurements and previous data predicted based on the uniform applied magnetic field along with the ballistic form of the demagnetizing factor.