Chapter 2: Installing the system
TT-98-129218-A
Placing the antenna
7
Radar distance
The minimum acceptable separation (d min.) between a radar and the antenna 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 and S band. If
the d min. separation listed below is applied, antenna damage is normally avoided.
“d min.” is defined as the shortest distance between the radar antenna (in any position) and the
surface of the SAILOR FleetBroadband antenna.
The separation distance for C-band (4-8 GHz) radars should generally be the same as for X-band
radars.
Interference
Even at distances greater than “d min.” in the previous section the radar might still be able to
degrade the performance of the SAILOR 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 favorable, this limited degradation is without importance.
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. A voice call might become noisy and perhaps fail
while a data connection might decrease in speed and performance.
X-band (~ 3 cm / 10 GHz) damage distance
Radar power
d min. at 15°
vertical separation
d min. at 60°
vertical separation
0 – 10 kW
0.8 m
0.4 m
30 kW
2.4 m
1.2 m
50 kW
4.0 m
2.0 m
S-band (~ 10 cm / 3 GHz) damage distance
Radar power
d min. at 30°
vertical separation
d min. at 75°
vertical separation
0 – 10 kW
0.4 m
0.2 m
30 kW
1.0 m
0.5 m
50 kW
2.0 m
1.0 m
