In radar, what is the function of a corner reflector?

• A. Absorb energy
• B. Reflect energy back to the source, increasing RCS
• C. Scatter energy in all directions
• D. Delay the signal

Answer: (B)

Corner reflectors work by providing retroreflection: they return radar energy directly back toward the source. The trihedral shape, with three mutually perpendicular metal faces, causes an incident wave to bounce off the first surface, then the second, and finally the third, sending the energy straight back to the radar regardless of the angle of incidence. This produces a very large radar cross-section (RCS) and a strong echo from the backscatter direction. It’s not about absorbing energy, nor about scattering energy uniformly in all directions, nor about intentionally delaying the signal—the key feature is the retroreflection that concentrates energy back to the radar.