Radar cross section (RCS) is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.
Covert, Military - R&D
Measurement of a target's RCS is performed at a radar reflectivity range or scattering range. The first type of range is an outdoor range where the target is positioned on a specially shaped low RCS pylon some distance down-range from the transmitters. Such a range eliminates the need for placing radar absorbers behind the target, however multi-path interactions with the ground must be mitigated.