The ferromagnetic Faraday effect at microwave frequencies and its applications: The microwave gyrator

A new microwave circuit element dependent on the Faraday rotation of a polarized wave has been developed. The element violates the reciprocity theorem and, because it shares this property with a gyroscope and because it is dependent on gyromagnetic resonance absorption, it has been termed a microwave gyrator. It is a low-loss broadband device with many applications. Among these are one-way transmission systems, microwave circulators, microwave switches, electrically controlled variable attenuators and modulators.