A
parabolic (or
paraboloid or
paraboloidal)
reflector (or
dish or
mirror) is a
reflective surface used to collect or project
energy such as
light,
sound, or
radio waves. Its shape is part of a
circular paraboloid, that is, the surface generated by a
parabola revolving around its axis. The parabolic reflector transforms an incoming
plane wave traveling along the axis into a
spherical wave converging toward the focus. Conversely, a spherical wave generated by a
point source placed in the focus is reflected into a plane wave propagating as a collimated beam along the axis.