Developments of MIC circulators from 1 to 40 GHz

Techniques and geometries for MIC circulators employing ferrite discs embedded in dielectric substrates have been developed extensively at frequencies ranging from 1 to 40 GHz. This form of fabrication, in which fit of the ferrite disc and finish are important, has proved reliable in use and to be of low cost. At high microwave frequencies microstrip to waveguide transitions are used with quartz substrates, whilst at low frequencies conductor geometry may be modified to reduce overall size of circulators and matching sections. Medium power loads using inserts of barium ferrite have been developed which can be incorporated into the microwave ferrite disc. For extreme environments circulator inserts may be deposited by arc plasma spraying of ferrite powder.