Types of transmission line:

Open Wire:

Open wire transmission used in olden days for telephone communication.

The drawback of the open wire transmission is that it will easily absorb external noises in addition to the signal.

Cables:

Eg: Television cable, underground cables etc

Coaxial line:

Television cable

Coaxial cable used to connect to CRO

Waveguide:

Optic fiber cable and DTH transmitter/receiver are example of Waveguide. See transmission lines and waveguides intro...