THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 



Photograph of the experimental setup shown diagrammatically in Fig. 5. 



INTRODUCTION 



In a recent series of articles, Tellegen^ 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) 



Vl 



= -Si. 



V2 = 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. 



