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prime focus antenna (PFA)

A prime focus antenna (PFA) is a parabolic antenna

, which has the shape of a paraboloid, is circular, completely symmetrical and the focal point of the reflector dish is exactly in the centre of the dish. In contrast to central antennas, the centre of the dish of offset antennas

isnot centrally located in the middle, but is slightly offset. The LNB converter attached to the feed horn

islocated at this point. The reflector

reflects all radio beams hitting the reflector in the feedhorn.Prime Focus

Antenna (PFA), Photo: fta-sat-receivers.com

Antenna (PFA), Photo: fta-sat-receivers.com

The alignment of prime focus antennas corresponds to the line of sight to the satellite

. This means that the PFA antenna is arranged in a relatively open position, which can cause snow to accumulate in the reflector dish in winter and alter the reception characteristics. In addition, the radiator, which is located exactly in the centre of the dish, shades the main beam direction. PFA antennas include the double reflector parabolic antennas such as the Gregory antenna and the Cassegrain antenna.

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Englisch: prime focus antenna - PFA
Updated at: 20.10.2018
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Translations: DE