Chapter 2: Installing the system
TT-98-129218-A
Placing the antenna
6
Interference
Overview
The antenna must be mounted as far away as possible from the ship’s radar and high power radio
transmitters (including other Inmarsat based systems), because they may compromise the
antenna performance. RF emission from radars might actually damage the antenna.
The SAILOR FleetBroadband antenna itself may also interfere with other radio systems. Especially
other Inmarsat systems and GPS receivers with poor frequency discrimination are vulnerable to
the radiation generated by the SAILOR FleetBroadband antennas.
Radar
It is difficult to give exact guidelines for the minimum distance between a radar and the antenna
because radar power, radiation pattern, frequency and pulse length/shape vary from radar to
radar. Further, the antenna is typically placed in the near field of the radar antenna and
reflections from masts, decks and other items in the vicinity of the radar are different from ship to
ship.
However, it is possible to give a few guidelines:
Since a radar radiates a fan beam with a horizontal beam width of a few degrees and a vertical
beam width of up to +/- 15°, the worst interference can be avoided by mounting the antenna at a
different level – meaning that the antenna is installed minimum 15° above or below the radar
antenna. Due to near field effects the benefit of this vertical separation could be reduced at short
distances (below approximately 10 m) between radar antenna and the SAILOR FleetBroadband
antenna. Therefore it is recommended to ensure as much vertical separation as possible when the
SAILOR FleetBroadband antenna has to be placed close to a radar antenna.
Min. 15
Min. 15
