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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.

Look in the SatLex gallery for more pictures of Prime Focus dishes!
Advantages:
  • 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.
Disdvantages:
  • 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.
Further forms of Prime Focus antennas are Mesh, Cassegrain and Gregory.
The Mesh dish is a special form of the Prime Focus Antenna. A Mesh dish is made up of some kind of reticule. Just like the normal PFA, a Mesh dish is being used for C band reception using an Egis rotor.
Look in the SatLex gallery for more pictures of Mesh dishes!

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