case should power density in the fueling area be greater than would exist at a
distance of 50 feet (15 m) from radiated output of 250 watts. See Figure 9.
Bonding and Grounding. Where space limitations require the
location of fueling stations, parking ramps, or other structures near an
antenna site, all metal used in wooden structures within 200 feet (61 m) of
fixed antennas radiating 250 watts or more shall be bonded together and
grounded to reduce interference and fire hazards.
Antenna Position. If possible, antennas shall be positioned to
prevent radiation of fueling areas while in operation. Otherwise, minimum
distances given above shall be employed.
Isolation and Warning Devices
Fence. Only nonconducting materials are suitable for protective
fences for antennas. Usually, a wood fence from 4 to 6 feet high (1.2 to
1.8 m) will provide adequate protection. Gates shall be designed and
installed so that accidental entry into the hazardous area is not possible.
Warning Signs. Carefully worded and illustrated signs shall be
posted conspicuously to prevent personnel from contacting high-voltage leads
such as antennas and power supplies. Signs shall warn of the danger from all
forms of radiation and from all other sources. Warning signs for RF-radiation
hazards should be placed at eye level at the foot of ladders or other means of
access to all towers, masts, or structures where hazardous levels of radiation
occur or are likely to occur. In foreign countries, warning signs shall be
posted in English and in the appropriate foreign language, using warning
symbols appropriate for the country. Appropriate "HIGH-VOLTAGE" warning signs
shall be permanently and conspicuously posted in hazardous areas.
Equipment Shielding. To avoid EMI and RADHAZ problems, the
designer should take advantage of all inherent shielding offered by the
installation or system, as well as the terrain. Building components,
partitions, towers, and other similar structures may be used to advantage.
Equipment in a console or rack may be placed to take advantage of the inherent
shielding of the rack. Refer to NAVELEX 0101,106.
Obstruction Lighting and Marking. Poles and towers which are a
hazard to aircraft must be suitably marked for daytime visibility and lighted
at night by obstruction lights. A typical lighting system consists of a
automatically turns the lights on at dusk and off at dawn. The markings and
the number of lights required for a tower depend on its height. Refer to
0101,104. Tower lighting and marking shall comply with the latest
revision of Federal Aviation Agency (FAA) AC 70/7460, Obstruction Marking and