Coil quality

The coil quality Q is a special quality factor in electrical engineering . It represents the ratio of the reactance X _L to the effective resistance R of a coil :   

${\displaystyle Q={\frac {X_{L}}{R}}}$

The reciprocal of the coil quality gives the loss factor  d or the tangent of the loss angle  δ:

${\displaystyle {\frac {1}{Q}}=d=\tan \delta }$

The coil quality influences the properties of a resonant circuit , especially in the vicinity of the resonance frequency : With a high coil quality, the damping of the resonant circuit is lower than with a low coil quality. As a result, it has an influence, for example, on the selectivity of resonant circuits in radio receivers or on the power loss in transformers . In many cases a high quality coil is sought.

The coil quality is reduced by losses in the coil. This includes:

• Losses in the winding (direct current and eddy current losses )
• Losses in the core (eddy current and magnetic reversal losses )
• Losses due to eddy currents in the area or shielding
• Radiation losses .

literature

• Eugen Philippow (editor): Taschenbuch Elektrotechnik, Volume 3 . Verlag Technik, Berlin 1969.
• http://www.radiomuseum.org/forumdata/upload/Guetemessung%20mit%20Rechtecksignal%2Epdf