Installation manual

Site Survey 6009-33 Installation Manual
2-3
When the g-force exerted on the antenna is light, antenna stabilization and overall performance will not be affected.
If the g-force exerted on the antenna is high enough (> 1 G), antenna stabilization and overall performance will be
affected.
If the g-force exerted on the antenna is excessive (1-2 Gs), the antenna will not maintain stabilization and may even
be physically damaged by the g-force.
2.5. Mast Configurations
Sea Tel recommends the ADE be mounted on the ship in a location which has both a clear line-of-sight to the target
satellites in all potential azimuth/elevation ranges and sufficient support against vibration excitement. If possible,
mounting the ADE pedestal directly to ship deckhouse structures or other box stiffened structures is preferred.
However, in many cases, this imposes limits on the clear line-of-sight the antenna system has.
Often the solution for providing the full azimuth/elevation range the antenna needs is to mount the ADE on the ship’s
mast. Unfortunately, masts do not consider equipment masses in design and often have harmonic frequencies of their
own.
There are many designs of masts used on ships – masts are nearly as unique in design as the ship is – but the designs
often fall into just a few categories. These categories can be addressed in terms of typical responses and problems
with regards to vibration and mounting of ADE. The most common categories of masts are:
2.5.1.
Vertical masts are a very ancient and common mast design. In essence, it is the mast derived from the sailing
mast, adapted for mounting the ever-increasing array of antennae ships need to communicate with the
world. This drawing of a Vertical mast shows
preferred mounting of the ADE center-line above
the plane of the radar, or as an alternate with the
ADE mounted below the plane of the radar signal,
as reasonably good installations of a satellite
antenna ADE.
Vertical Masts
Vertical masts are most commonly still found on
cargo ships – they are simple, inelegant and
functional. They are also fairly stiff against
torsional reaction and lateral vibrations, as long as
the ADE is mounted on a stiff pedestal near the
vertical centerline of the mast. If centerline
mounting is impractical or otherwise prohibited,
the mast platform the ADE is mounted on should be checked for torsional vibration about the centerline of
the mast and the orthogonal centerline of the platform.