Transmission line distortion and loading

The main two varieties of distortion in transmission line are frequency distortion and phase distortion ( or delay distortion). Both frequency distortion and phase distortion are not due to any non-linearity of the system and hence they are linear distortions. The correction for frequency distortion in a transmission line is possible by using a two-port network, called equalizer. This network is mounted at the receiving end which is designed to have transmission loss complementary to that of the particular transmission line used at least over the bandwidth of interest. Measurement of phase distortion is carried out in terms of delay distortion coefficient.  Delay distortion coefficient which is also known as differential delay is the difference between the maximum and minimum group delays for frequencies within a specified band. Four methods that can be adopted for a distortion less line are reducing R, increasing G, reducing C and increasing L. Increasing the inductance (L) of the line is called loading. There are two types of loading mechanisms- continuous loading and lumped loading. In continuous loading, inductance of the line is increased uniformly along the length of the line. In lumped loading, inductance coils are wound on torroidal magnetic dust cores which are connected periodically and in series with the transmission line.