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High Q air core inductance

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baby_2

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High Q air core inductanne

Hi,
In deigning air core the book mentioned for increasing and improving the quality factor of an air core we should close spaced windings. However, in another reference, as I remember,"The windings can be separated to reduce the inter-winding capacitance which in turn will increase the Q facotr"

Now, for high Q what should I do? make the space smaller or bigger?
 

Re: High Q air core inductanne

Hi
If you're interested, I can send you a small java program for calculating air coils.
air coil.png

- - - Updated - - -

With the online coil calculator
https://hamwaves.com/antennas/inductance.html
you get the same results as with the java tool. I did a lot of 3D simulations (CST) to check the accuracy of the tools.
Both tools deliver the same results and are good enough for practical use.
 
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Re: High Q air core inductanne

Thanks niki for your prompt response
I wil be grateful if you send the program's download link. In addition, do you know which formula did those software use?
 

Re: High Q air core inductanne

Air core Q is mainly limited by copper losses respectively skin effect. Inter winding capacitance and self resonance are not directly related to Q.

Design methods differ a lot depending on the frequency range. Low frequency coils take advantage from litz wire and special winding geometries.

Generally, there's no simple "formula" to calculate air core inductance. Existing formulas are purely empirical. 3D electromagnetic simulation is the way to get it exact.
 
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Re: High Q air core inductanne

FvM said:
Air core Q is mainly limited by copper losses respectively skin effect. Inter winding capacitance and self resonance are not directly related to Q.

Design methods differ a lot depending on the frequency range. Low frequency coils take advantage from litz wire and special winding geometries.

Generally, there's no simple "formula" to calculate air core inductance. Existing formulas are purely empirical. 3D electromagnetic simulation is the way to get it exact.
Click to expand...

I totally agree.
This is the reason for the java-tool. Of course not one simple formula, but many effects are taken into account.
If you are interested, test the tool and compare it with a reference design. I measured my coils and also simulated them with CST.

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Some information from the development of the tool... (in german)
Feldsimulierte Referenzspulen als Testobjekte für P2 meine Auswertung (2)_Seite_1.pngFeldsimulierte Referenzspulen als Testobjekte für P2 meine Auswertung (2)_Seite_2.pngFeldsimulierte Referenzspulen als Testobjekte für P2 meine Auswertung (2)_Seite_3.pngL1.pngQs.png
 
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Re: High Q air core inductanne

General rule of thumb for solenoids is to space the windings by one wire diameter (somewhere between 0.5d and 1.5d is usually fine).
 
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