What is insertion loss?
Often expressed in decibels or dB is defined as a 10*8 log (Po/Pi) where Po stands for power out and Pi that stands for power in.
What are the causes of insertion loss?
There can be 3 main causes of insertion loss-
Reflected losses- where the losses are caused by the VSWR of the connector.
Dielectric losses-losses caused by the power dissipated in the dielectric materials like Teflon, Rexolite, etc.
Copper losses-caused by the power conducting surfaces of the connector. It is a function of the material and plating used.
The insertion loss of a connector is on the order of a few hundredths to a few tenths of a dB. As with VSWR, it can be specified as a flat tine limit or a function of the frequency. Although the connectors are specified to operate over a wide frequency range, they are only specified for testing at a particular frequency because the test procedure required to obtain an accurate measurement of such small losses is a very precise and time-consuming process.