A fast-switching X-band circulator utilizing ferrite toroids

Non-reciprocal waveguide devices have been constructed utilizing permanently magnetized ferrite tubes. The use of ferrite elements of this geometry makes possible the realization of ferrite assemblies without the need of a magnet. For switching purposes the remanent state of the ferrite material may be reversed by the application of current pulses to a wire inserted through the tube. Utilizing this arrangement, a differential phase shift circulator has been developed which operates over the frequency range of 8.2 to 9.2 KMc. The loss between coupled ports is 0.6 db or less and the isolation between uncoupled ports is 2.5 db or greater. The circulator can be switched in less than
\frac{1}{2} \mu
sec. Permanently magnetized ferrite toroids have also been employed in waveguide T and coaxial geometries. Preliminary results are presented.