The subreflector is an asymmetrically shaped Cassegrain reflector that is a metal-coated carbon fiber/fiberglass-reinforced aluminum honeycomb design. It is 3.5 meters (~10') in diameter, and the surface accuracy is 0.150 mm (the highest-to-lowest deviation on the surface is not greater than 0.150 mm).

The asymmetrical shape of the subreflector creates a focusing point that points into the center of the feed horns located in the feed cone. As the subreflector moves in rotation, this focusing point travels around the top of the feed cone in a circle and crossing through the center of the different feed horns.

The subreflector can also travel up or down in order to focus the signal into the receiver located at the base of the feed horn. The only receiver that is not located in the feed horn is the 74/327/610 MHz [4m/90/50cm] dipole that is sticking out of the bottom of the subreflector.