Attenuation:When a signal travels through a transmission medium, part of its energy is converted into heat or absorbed by the medium, causing the signal strength to gradually weaken. This phenomenon is known as attenuation.

Signal attenuation is an important characteristic in communication transmission. The degree of attenuation not only serves as a key indicator for evaluating communication quality but also directly affects system expansion, repeater spacing, and other aspects of network design. Attenuation is related to the length of the cable—the longer the cable, the greater the attenuation. It is measured in decibels (dB), representing the ratio of signal strength between the transmitting and receiving ends.

Because attenuation varies with frequency, it should be measured across the full frequency range used in an application. The main causes of signal attenuation in network cables include the following:

1.Resistive Losses:
The conductor inside the cable (typically copper) has electrical resistance, which causes part of the electrical energy to be dissipated as heat, leading to signal loss. The resistance — and thus the loss — increases with conductor length and depends on material quality.

2.Dielectric Losses:
The insulating material (dielectric) surrounding the conductors also affects signal transmission. This material exhibits frequency-dependent dielectric losses — the higher the loss, the greater the signal attenuation.

3.Coupling Losses:
In multi-pair cables (such as twisted pairs), signals in one pair may couple into another pair, transferring part of the signal energy. This phenomenon, known as crosstalk, contributes to attenuation and signal degradation.

4.Shielding Failure:
For shielded cables (such as STP or FTP types), if the shielding layer is damaged or improperly grounded, it cannot effectively block external electromagnetic interference, resulting in signal loss.

5.Bending and Physical Damage:
Excessive bending, twisting, or mechanical damage during installation or use can cause attenuation. Over-bending may alter the cable’s internal geometry, affecting conductor spacing and signal transmission performance.

6.Environmental Factors:
Temperature and humidity also impact cable performance. Higher temperatures increase conductor resistance, while humidity changes can affect the dielectric properties of insulation materials.

To minimize signal attenuation, it is essential to select the appropriate cable type (such as Cat5e, Cat6, or Cat6a) based on the application environment and transmission distance, and to ensure proper installation and maintenance practices.