Site preparation
98-146706-A
Chapter 3: Installation
3-13
Installation
3.2.7
Interference from radar, GPS and other transmitters
Mount the ADU as far away as possible from the ship’s radar and high power radio
transmitters, because they may compromise the ADU performance. RF emission from
radars might actually damage the ADU.
The SAILOR 900 Ka ADU itself may also interfere with other radio systems.
Radar
It is difficult to give exact guidelines for the minimum distance between a radar and the
ADU because radar power, radiation pattern, frequency and pulse length/shape vary from
radar to radar. Further, the ADU is typically placed in the near field of the radar ADU and
reflections from masts, decks and other items near the radar vary 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°, you can
avoid the worst interference by mounting the ADU at a different level – meaning that the
ADU 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 900 Ka ADU. Therefore it is
recommended to ensure as much vertical separation as possible when the SAILOR 900 Ka
ADU has to be placed close to a radar antenna.
Radar distance
The minimum acceptable separation (d min.) between a radar and the ADU is determined
by the radar wavelength/frequency and the power emitted by the radar. The tables below
show some “rule of thumb” minimum separation distances as a function of radar power at X
Note
Do not place the ADU close to interfering signal sources or
receivers. For allowed distances to other transmitters see Figure
3-13:
Recommended distance to transmitters (m) for
testing the total system by operating all equipment
simultaneously and verifying that there is no interference.
Figure 3-12: Interference with the vessel’s radar
Min. 15°
Min. 15°
Radar
SAILOR900Ka-IM-98-146706.book Page 13 Thursday, July 16, 2015 11:07 AM
