Importance of the Dispersion Principles in System Design

Many of the components of Electrical engineering have been developed primarily to deal with the phenomenon of dispersion. Dispersion is a fact of life and it states that the phase/group velocity of a waveform is a function of its frequency. In optics this is reflected as the rainbow in the sky where the different components of white light separates out as it traverses through a dielectric medium namely the rain drop which disperses the various components into several colors as each color has a different velocity of propagation. In short even when propagating in free space since the phase velocity associated with each frequency is different there develops naturally a distortion phenomenon because of the variation of the phase velocity with frequency. In electrical engineering it is more subtle. It happens both in audio and radio frequency signals. Therefore to prevent the distortion of a transmitted message recourse is taken to modulation. There will be no modulation schemes if there is no dispersion! Modulation essentially takes a band of signals and generally translates them to a much higher frequency so that now the effective bandwidth of the same signal will be much smaller than what it would be in its base band. Since, now the translated frequencies through modulation has now effectively a smaller band of frequencies the distortion in that smaller band will be small and hence distortion will be absent for all practical purposes.