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

[Markus Vester <markusvester@aol.com>]

  ... 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 <andy.g4jnt@gmail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
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 <rik.strobbe@fys.kuleuven.be> 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