Constant-Resistance Networks of the Linear Varying-Parameter Type

The term "constant-resistance network" is generally used to describe a fixed network whose input impedance is a constant independent of frequency. The present paper generalizes the concept of constant-resistance networks by extending this concept to linear varying-parameter systems. It is shown that any self-dual variable network is a constant-resistance network and this result is used to obtain such constant-resistance structures as the lattice and the bridged-tee. Explicit expressions for the transfer functions of these structures are derived and an illustrative example involving a constant-resistance variant of Cowan\´s modulator is considered. In addition to self-dual structures, a non-self-dual type of constant-resistance network is described and the possibility of using this structure as a constant-resistance capacitive modulator is indicated.