Sea Tel 4009-9 BROADBAND-AT-SEA, Руководство по установке

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4009-9 Installation Manual Site Survey
2-2
2.2. Antenna Shadowing (Blockage) and RF Interference
At the transmission frequencies of C and Ku band satellite antenna systems, any substantial structures in the way
of the beam path will cause significant degradation of the signal. Care should be taken to locate the ADE so that
it has direct line-of-sight with the satellite without any structures in the beam path through the full 360 degree
ships turn. Wire rope stays, lifelines, small diameter handrails and other accessories may pass through the beam
path in limited numbers; however, even these relatively insignificant shadows can produce measurable signal loss
at these frequencies.
2.3. Mounting Foundation
2.3.1. Mounting on Deck or Deckhouse
While mounting the ADE on a mast is a common solution to elevate the ADE far enough above the
various obstructions which create signal blockages, sometimes the best mounting position is on a deck or
deckhouse top. These installations are inherently stiffer than a mast installation, if for no other reason
than the design of the deck/deckhouse structure is prescribed by the ship’s classification society. In the
deck/deckhouse design rules, the minimum plating and stiffener guidelines are chosen to preclude high
local vibration amplitudes.
Most installations onto a deck or deckhouse structure will require a mounting pedestal to raise the ADE
above the deck for radome hatch access and to allow the full range of elevation (see ADE mounting
considerations above). Some care must be taken to ensure the mounting pedestal is properly aligned
with the stiffeners under the deck plating.
2.3.2. ADE Mounting Considerations
Mounting the radome directly on the deck or platform
prevents access to the hatch in the base of the radome
unless an opening is designed into the mounting surface.
If there is no access to the hatch, the only way to service
the antenna is to remove the radome top. Two people are
required to take the top off of the radome without
cracking or losing control of it, but even with two people a
gust of wind may cause them to lose control and the
radome top may be catastrophically damaged (see repair
information in the radome specifications).
If access to the hatch cannot be provided in the mounting
surface, provide a short ADE support pedestal to mount
the ADE on which is tall enough to allow access into the
radome via the hatch.
Ladder rungs must be provided on all mounting
stanchions greater than 3-4 feet tall to allow footing for
personnel safety when entering the hatch of the radome.
The recommended cable passage in the 50, 60 and 66
inch radomes is through the bottom center of the radome base, down through the ADE support pedestal,
through the deck and into the interior of the ship.
2.3.3. Sizing of the support pedestal
The following should be taken into account when choosing the height of a mounting support stand:
1. The height of the pedestal should be kept as short as possible, taking into account
recommendations given in other Sea Tel Guidelines.
2. The minimum height of the pedestal above a flat deck or platform to allow access into the
radome for maintenance should be 0.6 meters (24 inches).
3. The connection of the ADE mounting plate to the stanchion and the connection of the pedestal