Introduction
CatX cable refers to various grades of twisted pair copper cabling used for Ethernet and other types of data networking. The “X” refers to the various categories (Cat5, Cat6, etc.) that specify the performance capabilities of the cable. CatX cables have either 4 or 8 copper wires twisted into pairs inside an outer jacket. The twisting helps reduce interference and crosstalk between the wire pairs.
The twisting pattern and spacing of the wire pairs makes CatX either end loaded or balanced in terms of impedance. End loaded cables have most of their impedance at the ends, while balanced cables have more even impedance along their length. End loaded cables work fine for short runs, while balanced cables allow for longer runs by preventing return loss. Understanding the difference helps select the right cable for an application.
This article provides an overview of the construction, performance, applications and standards related to end loaded versus balanced CatX cables. The goal is to help readers better understand the cable options to make informed decisions when purchasing and installing CatX cabling.
Construction of Catx Cable
CATx cable is constructed with 4 twisted pairs of copper wire, which are insulated and bundled together inside an outer protective jacket. Each twisted pair consists of two insulated copper wires twisted together, which helps reduce crosstalk and electromagnetic interference (PureLink AV).
CATx cable typically contains no shielding, unlike similar networking cables such as STP or FTP. Shielding is used to protect against electromagnetic interference, but also increases cost and cable diameter. Unshielded CATx relies solely on the twisted pair design for noise rejection (Black Box).
CATx cables are designed for 100 ohm impedance, matching the 100 ohm impedance of the networking equipment it connects. This impedance matching helps prevent signal reflection and attenuation (Adder).
End Loaded vs Balanced
Catx cable can be either end loaded or balanced in its construction. The main difference between the two is that an end loaded cable has different impedances at each end, while a balanced cable has the same impedance end to end.
In an end loaded cable, one end has a higher impedance and the other has a lower impedance. This is done by making the conductors thinner at one end and thicker at the other. The benefit of this design is that it prevents signal reflections back down the cable. However, the impedance mismatch can cause issues with return loss and power transfer efficiency.
A balanced cable has uniform impedance along its entire length by keeping the conductor size consistent. This provides good impedance matching and return loss characteristics. The tradeoff is that some signal reflection can occur. However, techniques like impedance matching networks can help mitigate this.
In summary, end loaded cables prevent reflections but have impedance mismatch issues. Balanced cables maintain uniform impedance and work well with impedance matching, but reflections may need mitigation. The choice depends on the specific application and transmission frequency.
Impedance
Impedance plays a key role in determining if a Catx cable is end loaded or balanced. Impedance refers to the opposition to alternating current in a cable and is measured in ohms. For Catx cables, the impedance is standardized at 100 ohms.
This standardized 100 ohm impedance allows Catx cables to reduce interference and signal reflection. Maintaining this impedance along the entire length of the cable is what defines a balanced Catx cable. If the impedance varies significantly between cable segments, it is considered end loaded.
According to CATx Wireline and Network Cable Simulators, balanced Catx cables maintain the 100 ohm impedance across all 4 pairs along the cable’s length. However, end loaded cables can have impedance mismatches of up to 20% between cable segments.
To achieve the balanced 100 ohm impedance, Catx cables are manufactured with twisted pairs of conductors. The twists help cancel out any electromagnetic interference picked up by the cable. A balanced 100 ohm impedance ensures proper performance and reduces signal loss across the entire cable length.
Applications
Catx cables commonly see use in:
- Ethernet networks
- Telephone systems
- Security camera systems
- Audio and video setups
Whether an end loaded or balanced cable is preferred depends on the specific application. Balanced cables with equal impedance throughout the length are generally recommended for long cable runs to avoid signal degradation. They provide good protection against electromagnetic interference over longer distances.
However, for shorter patch cable connections, an end loaded cable may be acceptable. The end loading helps compensate for impedance mismatches with connectors and equipment. This can optimize performance for patch cables up to 50-100 feet in length.
Overall, a balanced cable is a safer choice for general use across multiple applications. But end loaded cables have some benefits for short patch cable connections where impedance control and signal matching are critical. The needs of the specific application should determine which type of cable is selected.
Performance
When comparing end loaded vs balanced CATx cable, there are some key performance differences to consider:
Speed/Frequency – End loaded CATx cables tend to support higher frequencies and data rates than balanced cables. The end loading allows the cable to minimize impedance discontinuity effects and enables 10 Gbps transmissions up to 55 meters. Balanced CATx is generally limited to 1 Gbps speeds up to 100 meters. So for higher speed networks, end loaded provides an advantage.
Interference Rejection – Balanced CATx with its symmetric design tends to reject electromagnetic interference and crosstalk better than end loaded designs. The balanced construction helps cancel out any interference or noise being picked up along the length of the cable. So for noisy environments, balanced cable has superior rejection.
Signal Loss – End loaded cables can experience higher signal loss at higher frequencies compared to balanced CATx. The asymmetric design leads to more discontinuities that can degrade the signal. Balanced CATx has lower loss thanks to its uniform impedance. So for longer cable runs, balanced CATx may allow greater distances before signal loss becomes an issue.
Cost
The cost of catx cable can vary significantly depending on whether it is end loaded or balanced. The main factors that impact cost are copper pricing and construction differences.
Copper is the primary material used in catx cables to conduct the electrical signals. Copper prices fluctuate regularly based on global supply and demand. In general, end loaded catx cables require more copper than balanced cables. This is because the extra weight at the ends necessitates thicker copper conductors. When copper prices rise, end loaded cables will be more expensive than balanced options using the same quality copper.
There are also construction differences that impact cost. Balanced catx cables distribute the weight evenly, allowing for a thinner gauge copper throughout the length. End loaded cables concentrate more material at the ends. This requires thicker copper near the ends and more complex manufacturing. The extra materials and production work result in a higher cost for end loaded catx cables compared to balanced cables.
Installation
Proper installation is critical for Cat6 cable to meet performance specifications. Two key factors are termination and pulling tension.
Cat6 requires more precise termination than previous Cat5 standards due to the increased frequency. The twisting of the cable pairs must be maintained as close as possible to the termination point to reduce crosstalk. Any untwisting should not exceed 0.5 inches. The termination connectors must also maintain the cable pair twists. Using a punchdown tool helps maintain the pair twists during termination.
Cat6 cable has a minimum bending radius of 4x the cable diameter. Sharp bends can cause internal damage to the twisted pairs. The cable jacket can also be damaged from overbending.
The maximum pulling tension for Cat6 is 25 pounds. Exceeding this can stretch the cable pairs, altering the impedance and causing crosstalk issues. Using a pulley system and lubricant helps reduce pulling tension when installing longer cable runs.
Following best practices for termination, bending radius, and pull tension ensures the cable meets Cat6 specifications after installation.
Standards
Catx cables are standardized by telecommunications industry associations to ensure compatibility and performance. The two main standards bodies for Catx cables are:
- Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA): TIA/EIA has developed standards such as TIA/EIA-568 that specify requirements for Catx cables in premises cabling systems. For example, TIA/EIA-568-C.2 specifies performance requirements for Cat6 cables.
- International Organization for Standardization/International Electrotechnical Commission (ISO/IEC): ISO/IEC has published standards for Catx cabling alongside national standards bodies. ISO/IEC 11801 is an international standard that specifies general requirements for Catx cable networks.
Adherence to standards from TIA/EIA and ISO/IEC ensures Catx cables will work as expected when installed in standardized structured cabling systems. The standards help establish cable performance characteristics like crosstalk, return loss, attenuation, and bandwidth.[1] [2]
Conclusion
In summary, the key differences between end loaded and balanced Catx cable are:
- End loaded Catx cable has higher capacitance and attenuation per foot compared to balanced Catx cable due to the difference in conductor sizes.
- Balanced Catx cable provides more consistent impedance and better high frequency performance across the entire length of the cable.
- End loaded Catx is lower cost but may not meet performance specifications for longer cable runs.
For most applications under 328 feet, end loaded Catx provides a cost-effective solution. However, for longer cable runs or high frequency applications like 10G Ethernet, balanced Catx is recommended to ensure reliable performance across the entire channel.
When planning new cabling infrastructure, carefully evaluate expected bandwidth needs, cable distances, and performance requirements. Prioritize consistent impedance and attenuation over the entire channel. For budget conscious installations under 328 feet, end loaded Catx is acceptable. But for future-proof systems, opt for balanced Catx cable to deliver reliable high frequency transmission.