This thesis work dealt with an electromagnetic modelling of non-uniformly biased Y-junction circulators for further design and achievement of structures ultraminiatures. Its originality stands in the development of a theoretical approach allowing a better description of the electromagnetic behaviour of the structure under study. This approach took into account both the non-uniformity of the static fields appearing in the structure (dc-bias field, demagnetizing fields and internal field) and the magnetisation state of the ferrite material. The realisation of an X-band microstrip circulator permitted the comparison of experimental results with theoretical ones issued from our approach and highlighted a degradation of the device performances because of the non-uniformity of the dc-bias field. Further to the changes made in our theoretical approach, we got the devices responses of self-biaised hexaferrite circulators operating at remanence.
