Furuno Inmarsat FleetBroadband FELCOM251 Installation Manual page 17

2. INSTALLING THE SYSTEM
Radar distance
The minimum acceptable separation (d min.) between a radar and the antenna is de-
termined 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 and S band. If the d min. separation listed below is applied, anten-
na damage is normally avoided.
"d min." is defined as the shortest distance between the radar antenna (in any posi-
tion) and the surface of the FleetBroadband antenna.
Min. distance, radar (X-band) and FleetBroadband antenna
Radarpower
12 kW
25 kW
50 kW
Min. distance, radar (S-band) and FleetBroadband antenna
Radarpower
30 kW
60 kW
The separation distance for C-band (4-8 GHz) radars should generally be the same
as for X-band radars.
Radar interference
Even at distances greater than "d min." in the previous section the radar might still be
able to degrade the performance of the FleetBroadband system.
The presence of one or more X-band radars within a radius up to 100 m could cause
a minor degradation of the signal-to-noise ratio during high speed and data calls. The
degradation will be most significant at high radar pulse repetition rates.
As long as receiving conditions are favourable, this limited degradation is without im-
portance. However, if receiving conditions are poor – e.g. due to objects blocking the
signal path, heavy rainfall or icing, low satellite elevation and violent ship movements
– the small extra degradation due to the radar(s) could cause poor call quality. For ex-
ample, a voice call might become noisy or fail, while a data connection might decrease
in speed and performance.
The presence of S-band radar(s) is unlikely to cause any performance degradation.
as long as the minimum distances (d min.) listed in the previous section are applied.
It is strongly recommended that interference free operation is verified experimentally
before the installation is finalized.
2-4
X-band
FELCOM501
d min. at d min. at
15°verticals 60°verticals
eparation eparation
0.8 m 0.4 m
2.4 m 1.2 m
4.0 m 2.0 m
S-band
FELCOM501
d min. at d min. at
15°verticals 60°verticals
eparation eparation
1.0 m 0.5 m
2.0 m 1.0 m
FELCOM251
d min. at d min. at
15°verticals 60°verticals
eparation eparation
0.8 m 0.4 m
2.4 m 1.2 m
4.0 m 2.0 m
FELCOM251
d min. at d min. at
30°verticals 75°verticals
eparation eparation
1.0 m 0.5 m
2.0 m 1.0 m