Superposition through phases of the far fields scattered by the spheres of an aggregate

•Far fields scattered by cluster are superposed using appropriate phases.•Scattering cross section and asymmetry parameter formulas are in closed form.•This approach shows a higher precision than that based on T-matrix.•Stability of the convergence of the results are tested.

The problem of scattering by an aggregate of spherical scatterers can be solved by resorting to the expansion of the field in terms of vector multipole fields. First, one has to determine the amplitudes of the multipole fields scattered by each one of the spheres. Then, one has to superpose the latter fields in order to get the field scattered by the whole aggregate. In this paper we show how the contributions to the scattering amplitude of the whole aggregate due to the fields scattered by the component spheres can be superposed through the use of appropriate phases, and how the relevant quantities of the whole aggregate can be calculated by this approach, whose usefulness is also discussed.