Site preparation
3-4
Chapter 3: Installation
98-146706-A
3.2.2
Obstructions (ADU shadowing)
The ADU is stabilized in 3-axis (plus skew) and can be used in environments with elevations
of -25° to + 125° to allow for continuous pointing even in heavy sea conditions. The ADU
beam is approximately 1 m in diameter for the first 30 m from the ADU. Beyond 30 m the
beam gradually widens so that it is approximately 5 m in diameter at 100 m distance. This
beam expansion continues with increasing distance. Any obstructions, such as masts,
funnels, bridge house etc. within this field can cause signal degradation or signal loss.
For optimum performance adhere to the following guidelines:
1. Place the ADU so that it has as much free line-of-sight as possible without any
structures in the beam through one full 360 degrees turn of the vessel.
2. Do not place the ADU close to large objects that may block the signal.
3. Elevate the ADU by mounting it on a mast or on a mounting pedestal on a deck or deck
house top to avoid obstruction.
Note
Note that due to the short wavelength at Ka band and the
narrow beam width of the ADU even a
6 mm steel wire
placed within 50 m
inside the beam can causes signal
degradation.
Figure 3-1: Signal degradation because of obstructing objects
SAILOR900Ka-IM-98-146706.book Page 4 Thursday, July 16, 2015 11:07 AM
