Perhaps the biggest concern with radar is
that the highly focused beam of energy in the
microwave frequency range it transmits may
be harmful to people on board the boat, and
also can affect other onboard electronic
equipment. Most marine radars units installed
on recreational boats are X-band units, which
operate in the 8 GHz to 12 GHz frequency
spectrum. Some larger commercial craft may
also have S-band radar units, which operate in
the 2 GHz to 4 GHz spectrum.
The matter of whether or not radar is
harmful to people on board the boat is debat-
able. Cases of testicular cancer, cataracts, and
even behavioral changes have been attributed
to exposure to radar beams. After analyzing
data provided by the World Health Organiza-
tion (WHO), it seems clear to me that you
would have to be literally sitting in front of the
radome, say within 3 feet, for extended periods
of time to cause any ill effects. And even that is
not certain. In the United States, groups such
as the National Council on Radiation Protec-
tion (NCRP) are researching the possible car-
cinogenic, reproductive, and neurological
effects of human exposure to the levels of radi-
ation emitted by radar units. One thing we do
know for sure is that all the radar vendors will
discuss the potential safety hazards associated
with exposure to the radar beam and make
installation suggestions that will minimize the
possibility of this occurring.
As far as interference with other elec-
tronic equipment is concerned, WHO sums
it up like this: “Radars can cause electromag-
netic interference in other electronic equip-
ment. The threshold[s] for these effects are
often well below guidance levels for human
exposure to RF fields. Additionally, radars
can also cause interference in certain medical
devices, such as cardiac pacemakers and hear-
ing aids. If individuals using such devices
work in close proximity to radar systems they
should contact [the] manufacturers to deter-
mine the susceptibility of their products to
RF interference.”Ensuring Electromagnetic Compatibility
Radar manufacturers are concerned about elec-
tromagnetic compatibility (EMC), which is
the ability of electronic equipment to operate
in proximity with other electrical and elec-
tronic equipment without suffering from, or
causing, impaired performance. For our pur-
poses, it is essentially synonymous with EMI.
Improper installation of a radar set will almost
certainly guarantee problems with other
equipment as well as with its own perform-
ance. So we need some commonsense guide-
lines to help us achieve compatibility:- Keep radar and its connecting cables at
least 3 feet (1 m) from any other trans-
mitting equipment or cables carrying
radio signals, such as VHF radios. In the
case of SSB radios, double this separating
distance because SSBs are more powerful
than VHF radios. - Keep other antennas and electronic
equipment out of the radar beam’s path
by at least 6.5 feet (2 m). The radar beam
typically spreads about 12.5 degrees above
and below the radiating element (scanner)
on the radar. - Radar needs a power supply separate from
that of the engine starting motors. Equip
it with its own battery or a UPS device
(such as the Newmar unit mentioned in
Chapter 13) to prevent the unit from
blinking out and having to restart.
Voltage spikes and/or drops that occur
during engine cranking will often be
outside the voltage-operating parameters
for the radar. - If the cabling is equipped with a noise
suppression ferrite as shown in the photo,
installing communicationsand position-finding systems 153