Several Notes on Reciprocal Two-ports

Starting by ntroducing four common definitions on reciprocal two-ports,this paper provides the essential consideration on the word reciprocal and thus deduces the definition based on the port variables.Then this definition is proved to be equivalent to the definition based on the two-port parameters.The definition of the reciprocal element has then been given.The author also introduces that the reciprocal theorem is actually the simple statement that two-ports constituted by reciprocal elements are reciprocal and points out that it is only the sufficient condition for reciprocal two-ports.The relationship between reciprocal two-ports and passive two-ports has also been discussed.