The electromagnetic field, generated by a source, has four typical components: the far field, the middle field, the near field, and the self-field. This decomposition is studied with the help of the dyadic Green’s function for the electric field and its representation in reciprocal (<b>k</b>) space. The representations in <b>k</b> space involve three universal functions, which we call the <i>T</i>(<i>q</i>) functions. Various representations of these functions are presented, and an interesting sum rule is derived. It is shown that the magnetic field can be split in a similar way, leading to a middle field and a far field only.
© 2001 Optical Society of America
Henk F. Arnoldus, "Representation of the near-field, middle-field, and far-field electromagnetic Green’s functions in reciprocal space," J. Opt. Soc. Am. B 18, 547-555 (2001)