Furuno FELCOM251, Installation Manual

Page: 61 / 122

4. GROUNDING AND RF PROTECTION
4-8
4.5.2 Grounding the Antenna Unit
Communication Unit grounded at the hull (recommended)
In this case the antenna is grounded to the ship via one (or more) of its mounting bolts.
Make sure to remove painting, dirt, grease etc. at the mounting holes in order to make
good electrical contact to the hull. Use serrated washers when securing the mounting
bolts and seal the joint with protective coating to avoid corrosion.
Communication Unit grounded at a dedicated RF ground (alternative)
In this case the antenna is grounded with a separate ground cable. The ground cable
must be routed parallel and close to the shielded coax cable connecting the antenna
to the Communication Unit grounding kit. A tinned heavy gauge wire (min. 6 mm
2
) can
be used for this purpose – see section 4.8.2.
Note: The antenna must be electrically isolated at its mounting bolts by means of
shoulder bushings and washers ensuring the isolated RF ground – see section 4.9.3.
Recommended Alternative
Antenna
Unit
Mast
(electrically bonded
to the steel hull)
Mast
(electrically bonded
to the steel hull)
Base Plate
(electrically bonded to
the hull through the mast)
Base Plate
(Antenna isolated
from the hull)
Antenna grounded
with mouting bolts Antenna grounded
with separate cable
Antenna
Unit