Figure 3-33 A Radio Telescope Recall that the secondary mirror or prime focus on most telescopes blocks incoming light or other radiation. This radio telescope at the National Radio Astronomy Observatory in Green Bank, West Virginia, has its prime focus hardware located off-center from the telescope’s 100-m by 110-m oval reflector. By using this new design, there is no such loss of signal from equipment covering part of the telescope, unlike the effects of secondary mirrors on optical telescopes. Such configurations are also common on microwave dishes used to receive satellite transmissions for home televisions.