irst find the magnitude of the clutter return. Assume that the clutter fills the cell containing the target, that scatterers are statistically independent and that the scatterers are uniformly distributed through the volume. The clutter volume illuminated by a pulse can be calculated from the beam widths and the pulse duration, Figure 1. If c is the velocity of light and au is the time duration of the transmitted pulse then the pulse returning from a target is equivalent to a physical extent of c au, as is the return from any individual element of the clutter. The azimuth and elevation beamwidths, at a range R, are heta/2 and phi/2 respectively if the illuminated cell is assumed to have an elliptical cross section.