Waveguide circulators for the millimeter-wave region

The Y-circulator, which was first described by Chait and Curry (1959), is considered, taking into account its characteristics and its applications. The circulator properties are determined by the employed ferrite materials. The physical characteristics of ferrite materials are examined, and basic considerations regarding the circulator function are discussed. A description is given of the design of millimeter-wave circulators, taking into account circulators for the frequency range from 90 to 100 GHz. It is pointed out that the mechanical accuracy requirements for the manufacture of components used at higher frequencies become more exacting with increasing frequency. Attention is given to suitable milling techniques, aspects of ferrite and magnet selection, the design of the circulator casing, and the dimensioning of the ferrite cylinder. Experimental results are presented for a Y-circulator constructed according to the considered design.