CIRCULAR MIL -- A unit of area equal to the area of a circle whose diameter is one mil (1 mil = 0.001
inch). A circular mil is equal to π/4 or 78.54 percent of a square mil (1 square mil = 10 square inch). The
area of a circle in circular mils is equal to the square of its diameter in mils.
CIRCUIT -- An electronic closed-loop path between two or more points used for signal transfer.
COMMON-MODE VOLTAGE -- That amount of voltage common to both input terminals of a device.
COMMON-MODE REJECTION -- The ability of a device to reject a signal which is common to both its input
CONDUCTED INTERFERENCE -- Undesired signals that enter or leave an equipment along a conductive
COPPER CLAD STEEL -- Steel with a coating of copper bonded on it.
COUPLING -- Energy transfer between circuits, equipments, or systems.
COUPLING, CONDUCTED -- Energy transfer through a conductor.
COUPLING, FREE-SPACE -- Energy transfer via electromagnetic fields not in a conductor.
CUTOFF FREQUENCY -- The frequency below which electromagnetic energy will not propagate in a
DEGRADATION -- A decrease in the quality of a desired signal (i.e., decrease in the signal-to-noise ratio or
an increase in distortion), or an undesired change in the operational performance of equipment as the result of
DOWN CONDUCTOR, LIGHTNING -- The conductor connecting the air terminal or overhead ground wire to
the earth electrode subsystem.
EARTH ELECTRODE SUBSYSTEM -- A network of electrically interconnected rods, plates, mats, or grids
installed for the purpose of establishing a low resistance contact with earth.
ELECTRIC FIELD -- A vector field about a charged body. Its strength at any point is the force which would
be exerted on a unit positive charge at that point.
ELECTROMAGNETIC COMPATIBILITY (EMC) -- The capability of equipments or systems to be operated in
their intended operational environment, within designed levels of efficiency, without causing or receiving
degradation due to unintentional EMI. EMC is the result of an engineering planning process applied during the
life cycle of equipment. The process involves careful considerations of frequency allocation, design,
procurement, production, site selection, installation, operation, and maintenance.