2. The parabolic reflector on a reflector-type antenna system may be fed by a front- or rear-feed system. In a
front-feed system, the waveguide is curved around the edge of the reflector as shown in A of Figure 2-9. In a
rear-feed system, the waveguide passes through the reflector from the back side as shown in B of Figure 2-9.
Figure 2-9. Reflector feed systems.
LEARNING EVENT 11: CASSEGRAINIAN ANTENNA
A cassegrainian antenna is a rear-fed antenna which uses two reflectors to concentrate the electromagnetic
energy into a narrow beam. The antenna system is composed of a feed system, a hyperboloidal reflecting
surface, as shown in Figure 2-10. The waveguide horn illuminates the hyperbolic subreflector which, in turn,
illuminates the main parabolic reflector. Use of the hyperboloid ensures a more uniform illumination of the
main paraboloid.
SS0031
2-10
Previous Page
