In our modern, high-tech world, cables are more than just four pairs of wires bound together in a casing to connect electronic objects to each other. Cables, in fact, are a necessary component that keep our planet connected. Most of today's connectivity relies on shielded and unshielded cable.
STP and UTP Cables
Shielded twisted pair cable (STP) has the individual pairs of wires wrapped in foil, which are then wrapped again for double protection. Unshielded twisted pair cable (UTP) has each pair of wires twisted together. Those wires are then wrapped in tubing without any other protection. UTP cables are less expensive, and a more popular type of cabling.
Why are Shielded Cables Necessary?
Knowing which cable to use for a specific application depends on the protection needed from power frequency and any electromagnetic interference (EMI). This is where shielded vs. unshielded cable becomes important.
Preventing Electromagnetic Interference (EMI)
Electromagnetic interference (EMI), or radio frequency interference (RFI) as it’s also referred to, is an electronic disturbance generated by external electronic or electrical sources such as electrostatic coupling, electromagnetic radiation, or electrical circuit noise. The truth is, EMI/RFI is all around us. Just like the static you may hear during a phone call, the same is true for networking. If the EMI ‘noise’ is strong enough it may interfere with the actual data traffic and prevent computers from ‘hearing’ each other. When this happens, data is lost and the network has to resend the information a second time. The more often this process is repeated, the more often the network slows down. Thus, EMI disturbances can lower performance of a circuit or prevent it from functioning properly. Data paths can be interrupted ranging from an increase in error rate to a complete loss of information.
Different Types of Shielded Cable
Shielded twisted pair cabling (STP) reduces electromagnetic and radio frequency interference from other devices and electronic objects to ensure a steady signal. Cables consist of a bundle of wires divided into four pairs. Each pair is twisted together to reduce crosstalk interference from the other wire pairs in the bundle. There are 3 different shielding configurations, each with their own level of protection:
- Braided (90% EMI shielding)
- Spiral (98% EMI shielding)
- Metal-coated Mylar or foil (100% EMI shielding)
When to Use Shielded Cable
Shielded cables are useful in any environments where there is a high chance of electronic interference, such as radio stations (telecom cable assemblies) and airports (aerospace cable assemblies). STP cables are also used in security systems to provide protection from power frequency and radio frequency interference, or in box builds where there are multiple different components operating in close proximity. As well as being protected from external interference, the shielding also keeps noise from exiting the cable, minimizing the chance of causing interference in other devices.
When to Use Unshielded Cable
Unshielded cable (UTP) does not utilize shielding to reduce interference. UTP cables are designed to limit electromagnetic interference by the way the pairs are twisted inside the cable. UTP cable is most suitable for office LANS and similar network cabling systems. While offering less protection from interference, unshielded cables are popular because they are
- Easy to install
The main disadvantage of UTP cables is their susceptibility to electromagnetic interference and radio frequency interference. They also have a smaller bandwidth compared to coaxial cables or fiber optic cables.
Build a Better Assembly with JEM Electronics
Whether to use shielded or unshielded cabling ultimately is determined by the intended application. To discuss your cabling needs, contact one of our experts at JEM Electronics; we'll be glad to assist you with your next project.