The decrease in power of a signal with increasing distance. Attenuation is measured in decibels, and it increases as the power of the signal decreases. The best cables (those exhibiting the least attenuation) are fiber-optic lines, and the worst cables are unshielded, untwisted-pair lines, such as the silver, flat-satin cables used in short-run telephone and modem lines.
In a LAN, attenuation can become a problem when cable lengths exceed the stated network specification; however, the useful length of a cable may be extended by the use of a repeater.