ABSTRACT
This chapter focuses on the spectral characteristics of the radiation produced by a time varying charge and current distribution, that is, its dependence on frequency or wavelength. It discusses the potentials in the Lorentz gauge, and the radiation fields far from the sources so as obtain the asymptotic expression for the potentials in terms of spatial Fourier transforms. Evidently, the effectiveness of radiation with a given wavelength and direction of propagation depends upon the Fourier analysis of the time and spatial dependences of the charges and currents. The chapter discusses spectral distribution for dipole radiation. The total energy radiated by a small system is calculated through the use either of the spectral distribution. As a simple application of the spectral distribution, a model in which a charged particle undergoes damped motion in a Hooke’s law potential is considered. The chapter discusses Lorentzian line shape for the energy radiated per unit frequency range.
