Spectral selectivity of complex point sources in non-redundant field representations

The paper shows that a number of complex point source (CPS) beams can be chosen on the basis of the selective properties of the beams in the spectral domain. Furthermore, the use of the CSP spectra as interpolating spectral functions also provides information about the right selection of the complex displacement. Before entering in these details, it is worth summarizing the concept of the degrees of freedom of the radiated field.