Coaxial
cable is an electrical
cable consisting of an inner conductor or several
un-insulated conductors tightly twisted together, often
surrounded by an spacer,
surrounded by an outer cylindrical conducting shield
(sheath), and usually surrounded by a final insulating
layer (jacket). The term coaxial comes
from the inner conductor and the outer shield sharing
("co-") the same axis. It is often used as
a high-frequency
transmission line to carry a high-frequency or broadband
signal but may also be used for frequencies as low as
audio frequency. The electromagnetic
field carrying the signal exists (ideally) only
in the space between the inner and outer conductors.
The shielding reduces interference from
external electromagnetic fields, although coax
cable does radiate energy, shielding does somewhat reduce
the possibility of a transmitting device causing undesired
interference through transmission line leakage.
