ATTENUATION

The decrease in intensity of a signal , beam , or wave as a result of absorption of energy and of scattering out of the path to the detector , but not including the reduction due to geometric spreading. [After JP1 ] Note 1: Attenuation is usually expressed in dB . Note 2: "Attenuation" is often used as a misnomer for " attenuation coefficient , " which is expressed in dB per kilometer . Note 3: A distinction must be made as to whether the attenuation is that of signal power or signal electric field strength .