Communication networks employ a variety of transmission
media ranging from copper wires to
satellite channels to transport user's information. The
transmission media is the physical path
for the communication signal. Transmission media can be
classified into two major categories :
guided media, which may constrain and guide the communication
signal, and unguided media,
which permits signal to be transmitted but not guide them.
Examples of guided transmission
media are metallic cable and optical fibres. Examples
of unguided transmission media are
the radio signals and satellite signals. An important
characteristic of these different media
is the bandwidth or simply the range of frequencies each
can transmit. In general, the
greater the bandwidth of a given media, the more it can
carry.
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