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Message-ID: <3.0.1.16.20011031103423.2d2f75ac@mail.cc.kuleuven.ac.be>
Date: Wed, 31 Oct 2001 10:34:23
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: Re: LF: Multi-layer loading coils
In-reply-to: <15yjWu-0FxNy4C@fwd05.sul.t-online.com>
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Hello Ha-Jo,

I believe in mult-layer versus single-layer coils there are 2 factors
having an opposite effect :
1. A multi-layer coil needs less wire for the same inductance = less copper
losses
2. A multi-layer coil will suffer more from the proximity effect (the Q of
coil is degraded by the proximity of the turns to each other, in a single
layer coil each turn has on 2 'neighbour' turns, in a multi-layer coil this
can be up to 8 'neighbour' turns)

Since in a single layer coil the proximity effeect can be minimized by
spacing the turns (spacing = wire diameter seems a good compromize) I
assume that in a multi-layer coil Q can be improved by spacing the layers
usng a low loss dielectric material.

Further I believe to have read somewhere that higher Q's can be achieved by
winding a multi-layer coil in 'chambers'.

73, Rik  ON7YD

At 01:46 31/10/01 +0100, you wrote:
>Dear all,
>
>concerning multi versus single layer coils I have been informed by DJ2EY who 
>employs two coils of different diameter as a variometer that the Q of the
total 
>coil is less when the smaller coil is fully immersed into the greater one.
It 
>seems that the metal of the inner coil increases the loss of the outer
coil (and 
>possibly vice versa).
>
>Therefore when a high Q is needed, a single layer coil would be the better 
>solution.
>
>HW?
>
>73 Ha-Jo, DJ1ZB