In STP each of the two copper wires are twisted together and coated with a dielectric insulator which functions as ground for the wires. The extra shielding in STP wiring protects the transmission line from the leaking of electromagnetic interference from and into the cable. STP cabling is often used in Ethernet networks, especially fast data rate Ethernets with Speeds in the range of 10 to 1000 Mbps.
The notable features of STP are:
It prevents interference efficiently than UTP, but it is more expensive and difficult to install.
The attenuation of UTP cable is much higher than co-axial or shielded twisted pair cable.
The drawbacks are:
If the metallic shielding is not grounded properly at both ends, the shield behaves as an antenna and picks up unwanted signals.
Because of its cost and difficulty with termination, STP is rarely used in Ethernet networks.
