Classical Electrodynamics · Problem 14.13

Radiating Systems, Multipole Fields and Radiation — John David Jackson

Physics — E&M · periodic-motion-discrete-frequency-spectrum

Problem

Show explicitly by use of the Poisson sum formula or other means that, if the motion of a radiating particle repeats itself with periodicity TT, the continuous frequency spectrum becomes a discrete spectrum containing frequencies that are integral multiples of the fundamental. Show that a general expression for the time-averaged power radiated per unit solid angle in each multiple mm of the fundamental frequency ω0=2π/T\omega_0 = 2\pi/T is: dPmdΩ=e2ω04m2(2πc)3∣∫02π/ω0v(t)×nexp⁡[imω0(t−n⋅x(t)c)]dt∣2\frac{dP_m}{d\Omega} = \frac{e^2\omega_0^4 m^2}{(2\pi c)^3}\left|\int_0^{2\pi/\omega_0} \mathbf{v}(t) \times \mathbf{n}\exp\left[im\omega_0\left(t - \frac{\mathbf{n}\cdot\mathbf{x}(t)}{c}\right)\right]dt\right|^2

Related theory

Browse the problem library