An article will help you understand what STP, SFTP, UTP, FTP and ASTP are respectively?

This article helps you clarify the types of network cables such as STP, SFTP, UTP, FTP, and ASTP! They mainly differ from the shielding structure and materials, which directly affect their anti-electromagnetic interference ability, cost and application scenarios.

Detailed analysis

Detailed description

1.  UTP  

Full name: Unshielded Twisted Pair (Unshielded Twisted pair)

Structure: This is the most common and fundamental type of network cable. It contains 4 pairs (8 wires) of insulated copper wires inside, with each pair of wires twisted together at a specific pitch (twisted pairs are a natural anti-interference means). There is no additional metal shielding layer, only the outermost PVC sheath.

Advantages

• Lowest cost: The material cost and manufacturing cost are the lowest.

• Most flexible, thinnest and lightest: Easy to lay and terminate.

• Simple installation: There is no need to consider the grounding issue of the shielding layer.

Disadvantage

The weakest anti-electromagnetic interference capability: It is easily affected by electromagnetic interference generated by nearby power lines, motors, fluorescent lamps, radio equipment, etc., which may lead to signal attenuation, increased bit error rate, and even connection interruption.

Application scenarios: Network cabling in the vast majority of households, offices, and environments with low electromagnetic interference. As long as the environmental interference is not significant, UTP (such as Cat5e, Cat6, Cat6a) can fully meet the requirements of gigabit or even 10-gigabit Ethernet.

2.  FTP

Full name: Foiled Twisted Pair (aluminum foil total shielded twisted pair) or Screened UTP (S/UTP).

Structure: Outside the 4 pairs of twisted wires, a layer of aluminum foil shielding is wrapped as a whole. The aluminium foil layer is usually attached to a layer of polyester film to increase strength. Under the aluminum foil shielding layer, the wire pairs themselves do not have separate shielding. The outermost layer is a PVC sheath. Usually, there is a grounding manifold in contact with the aluminum foil layer.

Advantages

• Compared with UTP, it has a better ability to resist external electromagnetic interference (mainly against high-frequency interference).

• The cost is lower than that of STP/SFTP/ASTP.

Disadvantage

• The aluminum foil layer is relatively fragile and is prone to generating tiny cracks when bent during installation, which affects the shielding effect.

• It is necessary to use shielded RJ45 crystal heads and information modules in conjunction. Moreover, the entire chain (lines, modules, patch panels, device ports) must be well grounded to exert the shielding effect; otherwise, the shielding effect may not be as good as UTP and may even introduce interference.

• It is slightly thicker and harder than UTP.

Application scenarios: Environments with moderate electromagnetic interference, such as those close to power lines, small computer rooms, and the edge areas of certain industrial environments. In situations where the requirements are higher than UTP but the budget or installation conditions limit the use of STP/SFTP.

3.  STP

Full name: Shielded Twisted Pair (shielded Twisted pair). This term is sometimes generalized, but strictly speaking, it refers to the structure described below.

Structure (strictly defined) : Each pair of twisted wires is individually wrapped with a layer of aluminum foil shielding. Then, the four pairs of wires that have already been individually shielded are all wrapped with a layer of metal braided mesh shielding. The outermost layer is a PVC sheath. It includes a separate ground busbar.

Advantages

It offers the highest level of shielding protection: Dual shielding (independent shielding of wire pairs + main woven net shielding) can effectively resist various electromagnetic interferences, including low-frequency and high-frequency interferences, as well as crosstalk between wire pairs.

Disadvantage

• The highest cost.

• The thickest, hardest and heaviest: Laying and terminating are extremely difficult and require specialized tools and techniques.

• The installation requirements are extremely strict: shielded connectors must be used, and it must be ensured that the shielding layer throughout the entire chain (from device to device) is continuous and perfectly grounded. Poor grounding can cause the shielding layer to become an antenna, introducing more interference instead, and its performance may be even worse than that of UTP.

Application scenarios: Harsh industrial environments with extremely strong electromagnetic interference, such as near large motors, frequency converters, arc welding equipment, and medical imaging equipment. Critical links in data centers with extremely high requirements for signal integrity. Usually, Cat6a or Cat7 and above grades are used.

4.  SFTP

Full name: Shielded Foiled Twisted Pair (double shielded Twisted Pair) or Screened Foiled Twisted Pair (S/FTP).

Structure: Outside the 4 pairs of twisted wires, two shielding layers are simultaneously wrapped: the inner layer is an aluminum foil shielding layer, and the outer layer is a metal braided mesh shielding layer. Note that the pairs of wires here do not have separate shielding themselves. The outermost layer is a PVC sheath. It includes the grounding busbar.

Advantages

• Combining the advantages of aluminum foil (excellent resistance to high-frequency interference) and woven mesh (excellent resistance to low-frequency interference, high mechanical strength, and good grounding performance), it provides a very powerful overall anti-electromagnetic interference capability.

• The shielding effect is usually better than that of FTP and approaches or is equivalent to the strictly defined STP.

• Compared with strict STP (Independent shielding of wire pairs), the installation is slightly easier (but still more difficult than FTP/UTP).

Disadvantage

• The cost is high (second only to strict STP and ASTP).

• It is coarser and harder than FTP/UTP.

• Shielding connectors and perfect grounding are also required.

Application scenarios: Industrial environments with strong electromagnetic interference, places requiring high reliability and signal integrity (such as automated production lines, control rooms), and environments that need to be laid over long distances and may pass through interference sources. Cat6a SFTP is a commonly used choice for 10-Gigabit Ethernet in interference environments. It is also often used for long-distance outdoor installation.

5.  ASTP

Full name: Armored Shielded Twisted Pair (Armored shielded Twisted Pair).

Structure: On the basis of strict STP (i.e., each pair of wires is individually shielded with aluminum foil + total woven mesh shielding) or SFTP (total aluminum foil + total woven mesh shielding), an additional layer of metal armor (usually steel tape or steel wire braiding) is added to the outermost layer. The armor layer provides physical protection and also has the functions of shielding and grounding. The outermost layer may also have a PVC outer sheath.

Advantages

• Provide the highest level of physical protection: The armor layer can effectively resist mechanical damage such as gnawing by rodents, heavy pressure, squeezing, and puncture by sharp objects.

• It also has a powerful electromagnetic shielding capability: The internal shielding structure (STP or SFTP) provides excellent anti-interference ability.

Disadvantage

• The cost is extremely high.

• Extremely thick, hard and heavy: The laying is extremely difficult and requires professional tools and personnel.

• The installation is the most complex: In addition to the strict requirements for shielding and grounding, the armor layer itself also needs to be properly grounded.

• The bending radius is very large.

Application scenarios: Harsh environments that require extreme physical protection, such as: direct underground installation (to prevent rodent and ant gnawing), areas prone to external force damage (factory floors, near heavy equipment), and special places with strict fire and explosion prevention requirements (the armor layer can provide certain protection).

Summary and selection suggestions

UTP: The king of cost performance, the first choice for environments with no or weak interference (home, office). Meet the vast majority of daily needs.

FTP: An economical Option for dealing with moderate interference. Make sure it is well grounded.

SFTP: The main force in dealing with strong interference, its performance and installation difficulty lie between FTP and strict STP. It is commonly used in industrial environments and places with high requirements. Make sure it is well grounded.

STP (Strictly Defined) : The ultimate shielding solution for dealing with extremely strong interference, but it has the highest installation difficulty and cost. It must be perfectly grounded.

ASTP: Special scenarios that require top-level physical protection (such as direct burial, rodent prevention, and heavy pressure) and are simultaneously subject to strong interference. The cost and installation difficulty are both the highest.

Key points to note

1. Grounding is the lifeline of shielded wires: FTP, SFTP, STP, and ASTP must use shielded crystal heads, shielded information modules, and shielded patch panels, and these shielded components need to be connected to a unified and good grounding system. Otherwise, the shielding layer will not only be ineffective but also become a source of interference. UTP, on the other hand, does not need to consider grounding at all.

2. Termination quality is of vital importance: The termination of shielded wires is much more complex than that of UTP and requires professional tools and skilled techniques; otherwise, the integrity of the shielding layer will be compromised.

3. Cable grades: All the above types have different performance grades (such as Cat5e, Cat6, Cat6a, Cat7, Cat8). The shielding type mainly addresses interference issues, while the cable grade (conductor quality, twist pitch, etc.) determines the bandwidth and transmission distance it supports. When making a choice, both should be considered in combination (for example, Cat6a SFTP).

4. Actual demand-driven selection: Do not blindly pursue high-level shielding. For families and ordinary offices, UTPCat5e/Cat6 is completely sufficient and the most economical and convenient. Shielded cables should only be considered when it is confirmed that there are interference issues or when the environment has special requirements, and the type with an appropriate cost-effectiveness ratio (usually FTP or SFTP) should be selected. ASTP and strict STP are only used in very specific professional scenarios.

I hope this article can help you clearly distinguish and understand these five main types of network cables and their application scenarios!