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 EMISSION. Electromagnetic energy propagated from a source by radiation or
conduction.
EQUIPMENT GROUND NETWORK. An electrically continuous network consisting of
interconnected grounding plates and structural steel elements.
determined or known equipment radiation characteristics. The zone includes
all space within which a successful hostile intercept of Compromising
Emanations is considered possible.
EQUIPOTENTIAL GROUND PLANE. A mass, or masses of conducting material which,
when bonded together offers a negligible impedance to current flow.
FACILITY GROUND SYSTEM. The electrically interconnected system of conductors
and conductive elements that provides multiple current paths to the earth
electrode system. The facility ground system includes the equipment ground
network and the equipment racks, cabinets, conduit, junction boxes, raceways,
duct work, pipes, and other normally noncurrent-carrying metal elements.
FAR FIELD. The region of the field of an antenna where the radiation field
predominates and where the angular field distribution is essentially
independent of the distance from the antenna.
FAULT. An unintentional short-circuit, (usually of a power circuit) between
energized conductors or between an energized conductor and ground.
FAULT PROTECTION SUBSYSTEM. This subsystem ensures that personnel are
protected from shock hazards and the equipment is protected from damage
resulting from faults, including short circuits that may develop in the
electrical supply and distribution.
FERROUS SHIELDING. A low electrical resistance and high magnetic permeability
material which provides a low reluctance magnetic and high conductivity path.
FIELD STRENGTH. A general term that means either the magnitude of the
electric field vector (in volts per meter) or the magnitude of the magnetic
field vector (in ampere-turns per meter). As used in the field of EMC/EMI,
the term "Field Strength" shall be applied only to measurements made in the
far field and shall be abbreviated as FS. For measurements made in the near
field, the term "Electric Field Strength" (EFS) or "Magnetic Field Strength"
(MFS) shall be used, according to whether the resultant electric or magnetic
field, respectively is measured. The EFS shall be expressed as V/M and the
MFS as A/M. In this near field region, the field measured will be resultant
of the radiation, inductive and quasistatic (1/r, 1/r.2-, and, if present, the
1/r.3-) components, respectively of the field where r is the distance from the
source.
FILTER. A device for use on power lines or signal lines, specifically
designed to pass only selected frequencies and to attenuate substantially all
other frequencies.
FORTUITOUS CONDUCTOR. Any conductor which may provide an unintended path for
intelligible signals; for example, water pipes, wire or cable, metal
structural members, and so forth.
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