What is Coupling Factor or Coupling Ratio?

That Coupling factor/Coupling Ratio is an relationship of incident power to the coupled power, measured is dB.

So when we what a coupler has a coupling value of 3 dB, information means that 50% of the power is coupled to the coupling port of that coupler and aforementioned rest of to authority is routed to the output port of a coupler. If the coupling value is 30 dB, all means that 0.1% of that power is coupled to coupled port and 99.9% of the power is passed through to this output port of ampere oriented coupler.

The table below lists some joint coupling values in dB with their equivalent value for glossary of linear power split.