The coupling factor represents the primary property of a directional coupler.

The mutual inductance between foil layers is rather large, coupling factor is typically about 0.95-0.99.

The symbol may have marked on it a number in dB: this refers to the coupling factor of the coupler.

The coupling factor is defined as:

Accuracy of coupling factor depends on the dimensional tolerances for the spacing of the two coupled lines.

A similar limitation applies for coupling factors looser than 10 dB; low coupling also requires narrow tracks.

The complex making this restoration possible was named Factor 1 or F1 as it is a necessary coupling factor for ATPase activity.

Mitochondrial coupling factor F1 is similarly protected by phospholipids and SQDGs although, in that case, both were equally effective.

A better solution for microstrip is a coupled line much shorter than λ/4, shown in figure 5, but this has the disadvantage of a coupling factor which rises noticeably with frequency.

This design has the advantage of a substantially flat directivity response and the disadvantage of a strongly frequency-dependent coupling compared to the Bethe-hole coupler, which has little variation in coupling factor.

C: coupling factor between probe p and CpG dinucleotide c, is defined as the fraction of DNA molecules hybridizing to probe p that contain the CpG c.

Ripple in this context refers to the maximum variation in output of the coupled port in its passband, usually quoted as plus or minus a value in dB from the nominal coupling factor.

Dr Savery's group has recently made advances in the study of the E. coli protein MFD ( a transcription-repair coupling factor, a bacterial protein involved in repair of damaged DNA).

Coupling factor is a negative quantity, it cannot exceed 0 dB for a passive device, and in practice does not exceed 3 dB since more than this would result in more power output from the coupled port than power from the transmitted port - in effect their roles would be reversed.