Insertion loss
From Wikipedia, the free encyclopedia
In telecommunications, insertion loss is the decrease in transmitted signal power resulting from the insertion of a device in a transmission line or optical fiber. It is usually expressed relative to the signal power delivered to that same part before insertion. Insertion loss is usually expressed in dB.
The insertion loss of a device (which may be a whole line) may also be referred to as attenuation. Line terminations play an important part in insertion loss because they reflect some of the power. Apart from this it is clear that not all of the power which is sent into the line at one end appears at the other. This is because of radiation losses, resistive losses in the conductor as well as losses in the surrounding dielectric. All of these effects can be conceptually modelled as various elements which make up the equivalent circuit of the line (see for example distributed and lumped element models). The loss which results from inserting a transmission line between a source and a load is called the insertion loss of the line. Signal loss that goes no where.
If the power transmitted by the source is PT and the power received by the load is PR, then the insertion loss is given by PR divided by PT. Clearly this ratio is always less than one, so it would be more correct to call the property "Insertion Gain". It is often called "Attenuation".
Definition - The Insertion Loss of a line is the ratio of the power received at the end of the line to the power transmitted into the line.
For maximum power transfer the Insertion Loss should be as small as possible. In other words the ratio PR/PT should be as close to 1 as possible, which in decibels means as close to 0dB as possible.
In an optical fiber system, insertion loss is introduced by things such as connectors, splices, and couplers.
63.226.24.145 15:52, 14 November 2006 (UTC)AM63.226.24.145 15:52, 14 November 2006 (UTC)==References==
