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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Difference Between Cat6 and Cat7

Since the Ethernet cable is characterized with the advantages, such as affordable price, fast transmission speed and good reliability, it becomes more and more popular with people. As technology continues to progress, Ethernet cable also has been improved over time to meet the increasing demand of bandwidth. Cat6 and Cat7 are two kinds of Ethernet cables for 10G Ethernet applications. Do you know the differences between them? Now, this passage will focus on the comparison between Cat6 and Cat7 from five aspects: frequency, transmission distance, wiring, cost and lifespan. First, let’s go to the overview of Cat6 and Cat7.

Overview of Cat6 and Cat7

As the sixth generation of twisted pair Ethernet cable, Cat6 contains four pairs of copper wire and utilizes all of these pairs for signaling in order to obtain the higher level of performance—supporting 10G Ethernet. In addition, it is backward compatible with the Cat3, Cat5 and Cat5e cable standards. With even more stricter specifications for crosstalk and system noise, Cat7 is designed to allow 10G Ethernet over longer distance. It also contains four twisted copper wire pairs, just like the earlier standards. And Cat7 is backward compatible with Cat5e and Cat6. Here is a figure of Cat6 cable reel and Cat7 cable reel.

Cat6 cable reel and Cat7 cable reel

Difference Between Cat6 and Cat7

It is obvious that Cat7 greatly improves the capacity and reliability of Cat6. So what is the difference between Cat6 and Cat7? This part will focus on five aspects—frequency, transmission distance, wiring, cost and lifespan.

Frequency

Cat6 can perform at a frequency of up to 250 MHz and works fine for normal speeds—10BASE-T, 100BASE-TX, 1000BASE-T, and 10GBASE-T standards. While the frequency of Cat7 is higher and up to 600 MHz, which is 2.4 times as fast as Cat6. And this makes Cat7 suitable for high-speed data rate transmission.

Transmission Distance

Cat6 can reach 100 meters for slower network speeds (up to 1,000 Mbps) and higher network speeds over short transmission distance—it can achieve only 55 meters at the speed of 10 Gbps and 33 meters in high crosstalk conditions. While Cat7 can operate at the speed of 10 Gbps with transmission distance up to 100 meters.

Wiring

Cat6 is available in both STP (Shielded Twisted Pair) forms and UTP (Unshielded Twisted Pair) forms. While Cat7 uses Screen Shielded twisted wire that not only reduces the chances of crosstalk, but also reduces the noise and enhances performance.

Cost

Cat7 costs more than Cat6. Take Fiberstore’s cables as an example, 100m Cat6 cable is 54.00 US$, while 100m Cat7 cable is 200.00 US$. The more cables you purchase, the bigger the price difference will be. Therefore, if your network needs 10 Gbps, maybe Cat6 is a more cost-effective choice.

Lifespan

Cat6 has an estimated lifespan of ten years. While for Cat7, shielding has been added for individual wire pairs and the cable as a whole. Because of this shielding, Cat7 is thicker, more bulky, and more difficult to bend. Cat7 is regarded as the most durable cable and has a longer lifespan of fifteen years than Cat 6.

Conclusion

Careful planning and product selection will be the key to a successful installation. Transmission speed, distance, cost and lifespan are the important factors that you should consider when choosing a transmission media. For 10G Ethernet applications, both Cat6 and Cat7 can be used. However, Cat7 is really high in cost when providing wider bandwidth with longer transmission distance. So you have to think carefully before making a decision. When it comes to make a choice between Cat6 and Cat7, I hope this passage can be helpful for you.