On the spatial bandwidth of scattered fields

It is shown that the scattered fields are almost space bandlimited functions. The effective bandwidth
W
is introduced and evaluated for a very general scattering system, as well as the error made using functions bandlimited to
w > W
for representing the scattered field. The effective bandwidth is very simply related to the maximum dimension of the scattering system; the error drops to negligible values for modest increases of
w
compared to
W
, in the case of large scatterers. Important consequences of the above general results are finally stressed.