Authors : Boualleg Ahcene , Merabtine Nadjim and Benslama Malek
Abstract: In this study, we use a point source at the focus, so that energy would radiate uniformly in all directions both in magnitude and in phase. The problem is that the energy that is not radiated toward the reflector will be wasted. What we really want is a feed antenna that only radiates toward the reflector and has a phase pattern that appears to radiate from a single point If we can illuminate the whole reflector, then we should be using the whole aperture. However, when we look more closely at the parabolic surface, we find that the focus is farther from the edge of the reflector then from the centre, because a part of the feed radiation misses the reflector; this loss called spillover. Another part of the feed energy is reflected back into the feed and doesn`t become part of the main beam; this loss is referred to as feed blockage. Ideally, all areas of the reflector should be illuminated with equal energy from the feed.
Boualleg Ahcene , Merabtine Nadjim and Benslama Malek , 2007. Trade off Between the Aperture Taper and Spillover Efficiencies of Prime Focus Reflector Antenna. Journal of Engineering and Applied Sciences, 2: 45-48.