It is shown that the scattered fields are almost space bandlimited functions. The effective bandwidth

is introduced and evaluated for a very general scattering system, as well as the error made using functions bandlimited to

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

compared to

, in the case of large scatterers. Important consequences of the above general results are finally stressed.