An Integrated Microstrip Circulator (Correspondence)

Ferrite circulators, incorporated as integral parts of a microstrip circuit on a copper-clad dielectric substrate, have been developed and tested. These circulators do not require the machining of a hole in the dielectric substrate or etching of the ferrite metalization. 20-dB isolation bandwidths of 3.5 to 4 percent in the frequency range 1.75 to 2.23 GHz were measured.