Free-field propagation of localized pulses

Incident transient fields obey homogeneous Maxwell equations and are assumed to be a known input to the integral equations of electromagnetic scattering. These fields can be specified by two solenoidal fields for and at the initial time, and they can be computed at other times using the Green function for the scalar wave equation. Equations are derived that are then used in a computer program to do the integrations over the information-collecting sphere. Sample calculations show that a modulated pulse keeps its shape much better than a simple pulse.