Open Wire
The traditional electrical wire used in telephone poles. No shielding or protection, therefore, creates noise from interference and hence not suitable for data transmission except for short distances under 20 ft.

Twisted Pair Cable
A twisted pair cable is made of two plastic insulated copper wires twisted together to form a single media.  One wire carries the actual signal and another is used for ground reference. The twisting is helpful in reducing noise (electro-magnetic interference) and crosstalk. Twisted pair invented by Alexander Graham Bell.









Used in Telephone and modem lines, Ethernet LANs.

How to make a cat 5e Cable

Coaxial Cable
Coaxial Cable consists of 2 conductors. The inner conductor is held inside an insulator with the other conductor woven around it providing a shield. An insulating protective coating called a jacket covers the outer conductor.

The outer shield protects the inner conductor from outside electrical signals.

Impedance
The distance between the outer conductor and inner conductor plus the type of material used for insulating the inner conductor determines the cable impedance.

75 ohms impedance for Cable TV, 50 ohms for Ethernet Thinnet and Thicknet.
The low impedance allows higher data rates to be transferred than Twisted Pair.