[Elecraft] Optimal Coil Dimensions

[Bob-AG5Q]

Belsley's result for optimizing a single layer coil is very interesting.
That's a clever change of variables to make the function differentiable :-)
It's nice to know the best geometry for this popular type of coil.
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Some links related to coils:

Wheeler's Equations for single layer and multilayer coils:

http://home.earthlink.net/~jimlux/hv/wheeler.htm

Rooks Coils (more efficient than ordinary solenoidal coils):
(so called because the coil form resembles the turret of a castle.)
It might be beneficial to combine this technique with Belsley's form factor.

http://www.geocities.com/rook_coils/

more pix of rooks coils:
http://www.schmarder.com/radios/crystal/23.htm

Does anyone know of a source of more detailed information on the rooks coil?
I've seen commercially manufactured coils like this before and I would like
to know how much better they really are.

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When a multilayer coil is an option, there is another winding geometry that
reduces the wire length even more:
Quoting from Ness Engineering's web page:

"A Brooks Coil is generally known as a special case of the circular coil
inductor of rectangular cross section that is implemented to achieve
the maximum inductance with a given length of wire."

The term "square coil" probably came about because of the square winding
crosssection of
the Brooks coil.
Although the Brooks geometry maximizes the inductance, it doesn't take into
consideration
the capacitance between turns. That might be significant at high
frequencies.

Read about the Brooks coil here:

http://home.san.rr.com/nessengr/techdata/brooks/brooks.html

NESS ENGINEERING has several pages of interest on basic electronic circuits:

http://home.san.rr.com/nessengr/techdata/techindex.html


73/ Bob - AG5Q