Chapter 2: Installing the system
TT-98-129218-A
Placing the antenna
10
Mast length and diameter
The placement of the antenna must ensure a rigid structural connection to the hull or structure of
the ship. Parts of the ship with heavy resonant vibrations are not suitable places for the antenna.
A small platform or short mast shall provide rigid support for the antenna fastening bolts and a
rigid interface to the ship.
If it is necessary to use a tall mast, use the table on page 11 to obtain the maximum free length of
the mast. Note that these values depend on rigid antenna-ship interfaces. The cross-sectional
properties and the corresponding maximum free length give a natural frequency above 30 Hz.
It is recommended to shorten the mast length as much as possible to obtain higher frequencies.
Alternatively, mount stays or wires to stabilize the mast further.
High masts or installations on ships with high vibration levels should be further stabilized by stays
or wires from the mast flange. Also mount vibration isolators between the flange and the radome.
For SAILOR 150 FleetBroadband, the vibration isolators are included in the Mast mount kit.
Note
The tables list the values for
steel masts
.
For
aluminium masts
, the free mast length is reduced to 75% of the values for steel.
Note
Stays and rigid masts can still not prevent vertical vibration if the mast is attached to a
deck plate that is not rigid. Make every effort to mount the mast on a surface that is well
supported by ribs. If this is not possible, provide extra deck plate propping.
Free
mast
le
ngt
h
(m)
OD (mm)
