The radio waves from the feed reflect back off the secondary reflector to the dish, which forms the outgoing beam.
Gregorian - Similar to the Cassegrain design except that the secondary reflector is concave, (ellipsoidal) in shape.
Six spokes connect the Hub to the Rim, passing through the secondary reflectors on the way.
A secondary reflector can have a complex geometry which allows it to break up the light and direct it to where it is desired.
The lamps are directed upward and shine their light onto wing-shaped secondary reflectors that spread the light out and direct it downward.
Like visible light, radar waves can be reflected from circular mirrors shaped as paraboloids, which focus the incoming radiation on small secondary reflectors.
A Gregorian reflector system was installed in 1997, incorporating secondary and tertiary reflectors to focus radio waves at a single point.
The secondary reflector of the Cassegrain design features an active surface.
Usually the secondary reflector and the feed antenna are located on the central axis of the dish.
It has a 305-m (1,000-ft) primary reflector fixed in position; the secondary reflector is on tracks to allow precise pointing to different parts of the sky.