Difference between shielded and unshielded cables
Release date: 2019-12-19 Browse times: 39
不仅仅是在壳体中将电子对象彼此连接的四对电线。 In our modern high-tech world, a cable is more than just four pairs of wires that connect electronic objects to each other in a housing. In fact, cables are a necessary component to keep our planet connected. Most connections today rely on shielded and unshielded cables.
STP and UTP cables
Each pair of shielded twisted pair cable (STP) wires is wrapped in foil and then wrapped again to provide double protection. Unshielded twisted pair cable (UTP) twists each pair of wires together. These wires are then wrapped in the pipe without any additional protection. UTP cable is cheaper and is a more popular cable.
Why do we need shielded cables?
Knowing the cables used for a particular application depends on the protection required for the power frequency and any electromagnetic interference (EMI). Here, shielded and unshielded cables become important.
Protection against electromagnetic interference (EMI)
Electromagnetic interference (EMI) or radio frequency interference (RFI) is also called electronic interference caused by external electronics or power sources (such as electrostatic coupling, electromagnetic radiation, or circuit noise). The truth is that EMI / RFI is everywhere. Just like the static electricity you hear on the phone, so is the network. If EMI is "noisy enough", it may interfere with actual data communications and prevent computers from "listening" to each other. When this happens, the data is lost and the network must send the message again. The more this process is repeated, the faster the network becomes slower. As a result, EMI interference can degrade circuit performance or prevent it from functioning properly.
Shielded twisted-pair cable (STP) reduces electromagnetic and radio frequency interference from other equipment and electronic objects to ensure signal stability. The cable consists of a bundle of wires divided into four pairs. Each pair is twisted together to reduce crosstalk from other pairs in the bundle. There are 3 different shielding configurations, each with its own degree of protection:
Braided (90% EMI shielding)
Spiral (98% EMI shielding)
Metal-coated polyester film or aluminum foil (100% EMI shielding)
When to use shielded cables
Shielded cables are useful in any environment where there is a high possibility of electronic interference, such as radio stations (telecommunications cable assemblies) and airports (aerospace cable assemblies). STP cables are also used in security systems to protect them from power frequencies and radio frequency interference. They can also be used in box buildings with many different components next to each other. The shielding layer not only prevents external interference, but also prevents noise from escaping from the cable, thereby greatly reducing the possibility of causing interference to other equipment.
When to use unshielded cables
Unshielded cables (UTP) do not use shielding to reduce interference. UTP cables are designed to limit electromagnetic interference by twisting twisted pairs inside the cable. UTP cables * are suitable for office LANS and similar network cabling systems. Unshielded cables, although they provide less protection against interference, are popular because they
1. Wide range of uses 2. Cheap 3. Easy to install 4. Lightweight 5. Flexible
The main disadvantage of UTP cables is their susceptibility to electromagnetic interference and radio frequency interference. They also have smaller bandwidths than coaxial or fiber optic cables.