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Re: LF: RE: Re: Antenna relays - multifilar Litz coil

To: [email protected]
Subject: Re: LF: RE: Re: Antenna relays - multifilar Litz coil
From: Markus Vester <[email protected]>
Date: Thu, 19 Nov 2015 17:48:58 -0500
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  ... but you could additionally increase wire diameter by sqrt(2) for the same coil length. Assuming skin effect regime, this will decrease R by another factor of sqrt(2). In other words, same coil Q at same coil size. In total, you get (2i)^2*R/2 => doubled power loss.
73, Markus

-----Ursprüngliche Mitteilung-----
Von: Andy Talbot <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Do, 19 Nov 2015 11:36 pm
Betreff: Re: LF: RE: Re: Antenna relays - multifilar Litz coil

That's a very interesting observation, and a simple calculation shows the way it will move:

If we add some extra || capacitance that is equal to that of the antenna, the loading coil inductance needs to be halved.   To a rough first approximation, the number of turns needed will reduce by SQRT(2) since L ~ N^2 , so the length of winding and coil R will lower by this amount too.  So R becomes R/SQRT(2)

Coil circulating current  will double,   so additional loss is 2 / SQRT(2)
SO worse, but not as bad as first thought

'jnt


On 19 November 2015 at 22:08, Rik Strobbe <[email protected]> wrote:

H
indeed, parallel capacitor will increase the coil current, but on the other hand you will get resonance with a smaller inductance. I haven't done any calculation on the case (yet), but probably both effects (larger current vs smaller coil) will more or less compensate each other.
 
73, Rik  ON7YD - OR7T

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