All About STP Cable

We know that EMI (electromagnetic interference) is a disturbance in twisted pair cables. It affects the performance of an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The primary way to combat EMI in cables is through the use of shielding. The shielding can act on EMI in two ways: first, it can reflect the energy; second, it can prevent the noise and conduct it to ground. With the help of cable shielding, cables can be immune to the disturbance and keep a stable connection. And this article will present some knowledge about STP (shielded twisted pair) cable.

Overview of STP Cable

First of all, let’s have a quick overview of STP cable. As the name suggests, STP cable has a metal shield around each twisted pair which is composed of copper tape, a layer of conducting polymer or a braid (made of copper or aluminum mostly). And the shield can be applied to each pair of the cable or to all pairs together. Typically, STP cable is more expensive than UTP (unshielded twisted pair) cable. And due to the fragile and rigid shield of STP cable, it is necessary to pay much attention to the installation and maintenance of STP cable.

Types of Shields

There are mainly two types of shields: braided shield and foiled shield. Braided shield is made up of woven mesh of bare or tinned copper wires. The braid makes it much easier for cable termination by crimping or soldering when attaching a connector. However, braided shield does not provide 100% coverage. It typically provides 70% to 95% coverage according to the tightness of weave. But as a matter of fact, 70% coverage is always sufficient if cables are fixed. Another shielding is foiled shield. This type of shielding uses a thin layer of aluminum. Because it is thin, it is harder to work with, especially when applying a connector. It provides 100% coverage for the conductors it surrounds.

As copper has higher conductivity than aluminum and the braid has more bulk for conducting noise, the braid is more effective as a shield. If the environment is extremely noisy, a cable may use multiple layers of shielding with both the braided and foil designs. Here is figure of braided shield, foiled shield and braided/foiled shield, from which you can have a better understanding of inner structure of these three types of shields.

braided shield, foiled shield and braided foiled shield

Different Constructions of Shielding

When you plan to buy shielded 100m cat6 cable on store, you may have to make a choice between different construction of shielding. And here are are some commonly used shielding constructions:

1) Individual Shield

U/FTP is the typical individual shielding using aluminum foil. This kind of construction has one shield for each twisted pair or quad above the conductor and insulation. Individual shield especially protects neighboring pairs from crosstalk.

2) Overall Shield

F/UTP, S/UTP, and SF/UTP are overall shielding with different shield materials. Overall shield refers to the entire coverage around the whole cable. This type of shielding helps prevent EMI from entering or exiting the cable.

3) Individual and Overall Shield

F/FTP, S/FTP, and SF/FTP are individual and overall shield. This type of construction has both layers of shielding. And its immunity to EMI disturbance is greatly improved.

Meanings of the abbreviated letters:

U = unshielded

F = foiled shielding

S = braided shielding

TP = twisted pair

Applications

Power cables are constructed with shielding to be electromagnetic compatible (EMC) to minimize noise generation, which affects many other systems like radio and data communication. Bulk Ethernet cables are shielded to prevent the effects on the data transmitted from EMI. To further prevent cross talk and coupling, some bulk Ethernet cables are also paired and individually shielded. In some applications, such as those needing servo cables, double or even triple, shielding is required around individual conductors, around twisted pairs, and around the entire cable. By the way, if you use shielded cat6 cable for your network, the cat6 patch panel you choose must be shielded, too.

Conclusion

Adopting twisted pair cable shielding is an effective method to prevent EMI from interfering signal transmission. For the purpose of providing a reliable connection between electronic devices, choosing a proper shielded twisted pair cable is essential. FS.COM provides various types of shielded cables, such as FTP cat5e cable 305m, SFTP 100m cat6 cable, SFTP 1000 feet cat6 cable.

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How to Choose the Right Ethernet Cable for Your Network?

To build your Ethernet network, the transmission media Ethernet cable is indispensable. And there are a variety of choices for Ethernet cables, such as Cat5e, Cat6, Cat6a and so on. If you are familiar with the differences between these different types of Ethernet cables, you may think it’s very simple to choose the right Ethernet cable for your network. However, is this really enough to help you make the decision? Are there any other factors you have to take into consideration? This article will give you the answer.

Overview of Different Types of Ethernet Cables

First, let’s have a quick review of the basic knowledge of these different types of Ethernet cables. For data speed, Cat5e is designed to support 1 Gigabit Ethernet with bandwidth up to 100MHz; Cat6 can support higher data rate of 10 Gigabit Ethernet with bandwidth up to 250 MHz; Cat6a is defined at frequencies up to 500MHz among 10G Ethernet applications. For transmission distance, Cat5e can reach 100 meters at the speed of 1Gbps; Cat6 is able to run 100 meters with data speed up to 1Gbps and only 55 meters at the speed of 10Gbps; Cat6a can support the distance over 100 meters at the speed of 10Gbps. Which types of Ethernet cables to choose depends on your requirement for transmission speed and distance. After you make a decision on this, there are some other factors you have to consider—straight-through or crossover cable, UTP (unshielded twisted pair) or STP (shielded twisted pair) cable, length and color. The following part will focus on these factors.

Straight-Through or Crossover Cable?

Ethernet cable terminated with RJ45 connector contains eight color-coded wires. The color-coded wiring sequences exist as a cabling industry standard. When linking RJ45 connector to a cable, there are two wiring standards—T-568A and T-568B. The two wiring standards are used to create a straight-through cable (T-568A or T-568B on both ends), or a crossover cable (T-568A on one end and T-568B on the other end). To choose a straight-through cable, you have to use either T-568A or T-568B on both ends of the cable; to choose a crossover cable, you need to wire T-568A on one end and T-568B on the other end of the cable. Here is a figure of T-568A and T-568B, from which you can see the difference between these two wiring standards.

T-568A and T-568B

UTP or STP Cable?

STP cable has a metal shield around each twisted pair which is composed of copper tape, a layer of conducting polymer or a braid (mostly made of copper or aluminum). With the shield, EMI (electromagnetic interference) and crosstalk can be greatly reduced, which enables the high performance of data transmission between different devices. While UTP cable has no shielding. It is designed to cancel electromagnetic interference through the way the pairs are twisted inside the cable. If the Ethernet cable runs in the environment where the interference or crosstalk is not the main concern, it is suggested to choose UTP cables which are lower in cost. But if the environment is full of powerful magnetic fields which may have an influence on the performance of network, STP cable is absolutely the optimal choice. To have a better understanding of the difference between UTP cable and STP cable, here is figure of the inner structure of UTP cable and STP cable.

the inner structure of UTP cable and STP cable

Length and Color

When choosing Ether cable for your network, you also need to consider length and color. Ethernet cable comes in standard lengths such as 1, 3, 5, 7, and 10 meter. Longer lengths are available, such as bulk Cat5e cable 305m. The distance between your various network devices and your network switch or router will determine the length you need. In addition, Ethernet cable is designed in all sorts of colors, such as blue, gray, red and some other color. This decision can be based purely on your individual taste and preference.

Conclusion

There is no doubt that choosing the right Ethernet cable can make your network work at a high performance level. I hope this article can help you know more about Ethernet cable and make the right choice for your network application. There are different types of Ethernet cables available in FS.COM, such as UTP Cat5e bulk cable, STP Cat6 bulk cable and so on. Also, they have different types of RJ45 couplers which can be a convenient way to combine two short Ethernet cables into a longer one, such as Cat6 coupler and Cat5e coupler.