The STP or Shielded Twisted Pair is a twisted pair cable that is additionally insulated by foil or/and braided copper shielding . This additional shielding is able to prevent external electromagnetic signals from affecting the signal traveling over the cable. Other purpose is to help to contain signal inside. The shielding might be grounded for better effect. Effect might be also increased by the type of material, its thickness, symmetry, consistency, and grounding mechanism. Of course different levels of noise give different effect.
Figure 1. Shielded twisted pair.
UTP or Unshielded Twiested Pair is not using any additional shielding, except of the plastic sheath around cable. It decreases the cost of the cable, but makes it less reliable in noise polluted areas.
Most common standards for UTP are shown in Table 1.
Table 1. UTP cables comparison.
Name
Bandwidth
Throughput
Details
Cat 3
16 MHz
10 Mbps
Cat 5
100 MHz
1000 Mbps
Cat 5e
350 MHz
1000 Mbps
High quality copper High twist ratio
Cat 6
250 MHz
6000 Mbps
Double foil insulator Fireproof plastic
Cat 6a
500 MHz
5 Gbps
Reduced attenuation
Backward compatibility
Cat 7
1 GHz
10 Gbps
Multiple shielding Requires different connector Larger size
Less flexible
UTP can be used with throughputs of up to 10 000 Mbps.
