Insertion loss

The insertion loss (English Insertion Loss, IL ) indicates the attenuation of a signal through a device that is inserted into a signal path. This may for example be a filter or a plug connection.

The insertion loss is the ratio between incoming and relaxed performance.

Since the insertion loss is expressed in dB, the following formula is used:

In filters and couplers, the insertion loss is mostly determined depending on the frequency area that is used by the desired signal.

The insertion loss can also be expressed by means of the scattering parameters (S- parameters) as: