Technology :: Antenna types for satellite reception
Prime Focus Antenna (PFA)
The Prime Focus Antenna (parabolic antenna) is a satellite antenna which is perfectly round. It is absolutely symmetric built and has a parabolic shape. The focal point is in the middle of the dish. That's why the LNB is mounted centrally at the focus, where it can collect all incoming signals. Such a satellite antenna is typically larger than 1.2 meters.
Because of its relatively large surface, the prime focus antenna is less sensitive to small directional deviations and there is a better chance of receiving signals outside the normal footprint. But on the other hand, because of the small beamwitdh (3dB) angle, the antenna has to be setup more accurate than a normal offset one.
Rain and snow can easily collect in the dish and could interfere with the signal.
Because of the LNB is mounted centrally, a lot of the incoming signals are blocked by the LNB on the way to the antenna surface. But if using only a Ku band feed, the shadow won't be that big as when using a C band feed.