Fourier spectra of the near fields from two-dimensional sources or scatterers in uniform motion

The theory of radiation from two-dimensional harmonic sources in uniform motion is studied. The fields detected by a stationary observer turn out to be rather complicated functions of time which exhibit both amplitude and phase modulation. Attention is focused on the frequency content of such signals. The method applies to sources with constant velocity and is valid for observers located in the near field or in the far field. Numerical results are presented for a moving line source. It is shown how the method can be extended to the spectra of the fields scattered by a two-dimensional moving body. This is illustrated by the case of a moving perfectly conducting circular cylinder immersed in an incident-plane E-wave.<>