Distortion in Linear Passive Networks

It is well known that distortion is suffered by a modulated wave in passing through a practical transmission network. The increasing use of frequency modulation in television relays and other uses where high fidelity is important has made the problem of FM distortion of current interest. One of the earliest analytical approaches to the problem was by Carson and Fry and later applied by Jaffe to single- and double-tuned circuits. The Carson and Fry method depends on a series solution to obtain numerical results. The theory to be developed is based on a series solution of the superposition integral. A recent approach along this line is by Bradley. He obtained a rapidly convergent series that is useful when the network transfer function is in a form which permits separation of attenuation and phase of the network and can be differentiated conveniently. It is the purpose of this paper to provide a method of calculating distortion, when the transfer function is known in pole and zero form, that is rapidly convergent under most cases considered in practice.