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Published: 12 April 2015

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The plugin screen.
Calculate influence of shield on the inductance value.
Shielded coil inductances most often used at high frequencies to guard the inductor from external electromagnetic fields. But the shield reduces selfinductance of the coil and its Qfactor, and also increases the parasitic selfcapacitance, and it's, of course, undesirable effect. To reduce the derating of the coil under the influence of shield on high frequences  the shield diameter should exceed the diameter of the coil is not less than 1.6  2.5 times, and for stable high quality coils  2.5  3 times. To estimate the degree of reduction of the inductance under the influence of shield Coil32 have a plugin that called "screen".
The calculation of the decreace of inductance due to the influence of the shield bases on the following empirical formula:
where:
 Ls  inductance of the shielded coil
 L0  inductance of the coil without shield
 Ds  diameter of shield
 H  height of shield
 D  diameter of winding
 L  length of winding
The formula is valid for cylindrical shield. In the case of a square shield in the input field enter the size of the side and then we can calculate the equivalent diameter, which is used in the above formula. The equivalent diameter is equal to average diameter of inscribed and circumscribed circles.
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