This weakens the power of the signal, irrespective of the transmission media used. Attenuation is expressed in decibels through the logarithmic ratio of the power measured at both ends of the distance being examined. Transmission media can usually be characterized by their attenuation per unit of length:

There are three factors to keep in mind when analyzing attenuation:

• It is directly proportional to the distance and frequency of the signal
• The signal must have enough power to be interpreted when it reaches its destination
• It must maintain a high enough level so that it is not confused with noise when it reaches its destination