A reflector consisting of three mutually perpendicular intersecting conducting flat surfaces, which returns a reflected electromagnetic wave to its point of origin. Note: Such reflectors are often used as radar targets. 2. A directional antenna using two mutually intersecting conducting flat surfaces. 3. A device, normally consisting of three metallic surfaces or screens perpendicular to one another, designed to act as a radar target or marker. 4. In radar interpretation, an object that, by means of multiple reflections from smooth surfaces, produces a radar return of greater magnitude than might be expected from the physical size of the object. 5. A passive optical mirror, that consists of three mutually perpendicular flat, intersecting reflecting surfaces, which returns an incident light beam in the opposite direction.