Insertion Loss

In telecommunications, insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in dBs. Insertion los(IL) is a measure of attenuation, but is a more precisely defined term. For instance, attenuation can include loss due to the source and load impedances not matching, but is not included in insertion loss since this is a loss that was already present before the "insertion" was made.

If the power transmitted to the load before insertion is PT and the power received by the load after insertion is PR, then the insertion loss in dB is given by,In metallic conductor systems, radiation losses, resistive losses in the conductor as well as losses in the surrounding dielectric all reduce the power. Line terminations play an important part in insertion loss because they reflect some of the power. All of these effects can be conceptually modelled as various elements which make up the equivalent circuit of the line.

In an optical fiber system, insertion loss is introduced by things such as fiber optic connectors, splices, and couplers.

June 7, 2011

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