The Ferromagnetic Faraday Effect at Microwave Frequencies and its Applications: The Microwave Gyrator

In a recent series of articles, Tellegen1 has discussed the possible applications of a new circuit element which he calls a gyrator. He defines the ideal gyrator, in principle, as a passive four-pole element which is described by: (see Fig. 1) vi = --Si 2 Vi = Sii (1) Since the coefficients above are of opposite sign, the gyrator violates the theorem of reciprocity. Any network composed of the usual electrical circuit elements--resistors, inductors, capacitors, and transformers-- will satisfy the theorem of reciprocity. In simple terms, this theorem states that if one inserts a voltage at one point in the network and measures the current at some other point, their ratio (called the transfer impedance) will be the same if the positions of voltage and current are interchanged. In the gyrator, however, this transfer impedance for one Fig. 1--General four-pole.