Isotropic target

From Glossary of Meteorology

isotropic target

In radar or lidar, a target that scatters the same intensity of radiation in all directions.

Specifically, for plane-wave incident radiation, an isotropic target scatters in all directions the same power per unit solid angle. Real targets are generally not isotropic, but scatter different intensities in different directions. The concept of an isotropic target is an artifice that allows the scattering properties of a real target to be described in terms of those of an equivalent isotropic target. Thus, the backscattering cross section of a target is the cross-sectional area of an isotropic target that scatters the same intensity in the direction of the radar receiver as the real target.
See phase function.