Integrated dc/rf design theory for ferrite circulators

An integrated design approach is described, in which the dc and rf aspects of circulator design are both addressed for a realistic physical model of the microwave ferrite. The microwave ferrite disc is conceptionally subdivided into a center puck and a sequence of rings, each of which may have a different magnetization. The dipole interaction between the rings is taken into account by means of a dipolar interaction matrix, which is a generalization of the conventional demagnetizing factor. The rf behavior of the ferrite (including off-resonance loss and “low-field loss”) is characterized by appropriate theoretical expressions derived on the same physical basis as the equations that characterize the dc behavior.