Coaxial cable
is an
electrical cable consisting of a round conducting
wire, surrounded by an
insulating spacer, surrounded by a
cylindrical conducting
sheath, usually surrounded by a final insulating
layer (jacket). It is used as a
high-frequency transmission line to carry a high-frequency
or
broadband signal. Because the
electromagnetic field carrying the signal exists
(ideally) only in the space between the inner and outer
conductors, it cannot interfere with or suffer
interference from external electromagnetic fields.

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