COBHAM SAILOR Fleet One Installationshandbuch PDF herunterladen (Seite 19)

Chapter 2: Installation

98-141368-A 11

Antenna mast design

The antenna mast must be designed to carry the weight of the antenna unit, which is

approximately 3.9 kg (+ 1.1 kg for the mast mount kit)

The mast must also be able to withstand onboard vibrations and wind forces up to 108 knots

on the radome, even in icing conditions.

Antenna mast mounting

Mast mount kit:

The top of the SAILOR Fleet One antenna mast should be fitted with the dedicated mounting

kit available from Cobham SATCOM.

Assemble the mast mount kit according to the assembly instruction included with the kit.

The mast mount kit interfaces to a 1½” pipe (OD 48.3 mm). If the supplied plastic sleeve is

omitted, a maximum diameter OD of 52 mm can be used.

Custom mast mounting:

For a custom mast mounting, use 4 M6 bolts (A4) in the threaded bushings on the 175.4 mm

diameter circle in the bottom of the antenna. The length of the bolts must be such that they

engage into the bushings of the radome with min. 6 mm and max. 12 mm.

Drill a hole for the cable in the mast flange or use an angled connector.

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 provides 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 12 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 Fleet One, the vibration isolators are included in the Mast mount kit.

Important

Do not block the drainage hole in the centre bottom of the antenna.

Note

The table in the next section lists the values for steel masts.

For aluminium masts, the free mast length is reduced to 75% of the values for steel.

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COBHAM SAILOR Fleet One Installationshandbuch Seite 19