2 feet above sea level with a 3-inch antenna
extended out of your flip phone.
Like VHF radio and radar, cell phones are
a line-of-sight system. So if we add a remote
cell phone antenna, we can “stretch” the hori-
zon out as far as possible. Like VHF antennas,
these are available with different gain ratings,
typically 3 dB and 9 db.
At least two companies—Shakespeare
(www.shakespeare-marine.com) and Digital
Antenna (www.digitalantenna.com)—make
combined VHF and cellular antennas. A device
splitter on the equipment end of the coaxial
cable allows both systems to be attached, but of
course they cannot be operated simultaneously.
The compromises already discussed in the
VHF section of this chapter apply here. A
3 dB antenna generally works better at the
masthead on a sailboat due to its wider beam,
which helps offset the effects of the boat’s
heeled position. A 9 dB antenna has a longer,
narrower beam. One compromise that works
on both powerboats and sailboats is the use of
an 8- or 9-foot whip, mounted on an exten-
sion pole set on a stern rail or on a dedicated
antenna-mounting system. The antenna lead
is usually terminated with a mini BNC-type
plug that inserts directly into the back of the
cell phone. (The socket is often hidden under
a cap; you may need to pry it out.)Radar Antennas
The most important consideration for a radar
antenna or scanner—besides its output rating
and whether or not it is an open or closed array
(dome)—is its position on the boat. Focusing
the antenna’s powerful emitted beam is impor-
tant to the accuracy and detail of the returned
signal. The power output from the antenna or
scanner is a guide to the expected range of the
unit—more power means more range. Most
radar antennas used on recreational boats have
outputs in the 2 kW to 10 kW range, andthese are matched by the manufacturers to
their respective display units. (Not all antennas
are compatible with all display units, even
those from the same manufacturer.)
These are powerful devices and safety must
be an important consideration:- Scanners have high-voltage components
and connections within their housings.
These units should only be serviced or
adjusted by factory-trained technicians. - Radar antennas transmit high-level electro-
magnetic energy that is dangerous to
humans. They should always be mounted
above head height or well below it, depend-
ing upon the boat configuration. On a sail-
boat, this is not a problem as the radar
antenna is mounted either on a raised
mounting pole far aft or well up the mast.
It is sometimes a problem on a powerboat
as the antenna sometimes gets mounted
forward of a flybridge deck directly in front
of the operator at the upper helm station.
This configuration should be avoided! - Never look directly at a scanner when it is
operating, and keep people out of the
emitted-beam path, which covers a full
360 degrees. - There are strict international regulations
that cover radar and its emissions. Some
units that are available in the United
States do not comply with European
Union regulations, and may not be used
there. The manufacturers usually make
this information readily available. In the
United States, the FCC regulates radar
use; in Canada, it is regulated under the
Canadian Shipping Act. As of this writ-
ing, efforts are underway to integrate
Canadian and U.S. requirements.
Like VHF radio, radar is a line-of-sight
device, so a higher scanner mount will give the
unit greater potential range. But as with VHF,184 marine electronics installation and troubleshooting