Topband: RX antenna transformer winding (pure resistance transformation issues)

[Jim Brown]

On 8/20/2013 11:31 AM, Don Kirk wrote:
> But I saw the complex impedance phenomena even with smaller diameter cores
> (using different grade of material), and here is my actual FT 50-43 data as
> an example.

One missing piece in understanding what you're seeing is the fact that 
mu (permeability) is a complex number, u' +ju'', where u' represents the 
inductive component and u'' represents the loss component for series 
equivalent circuit elements.  Here's a link to the Fair-Rite data sheet 
for #43 material.

http://www.fair-rite.com/newfair/materials43.htm

Note that at 2 MHz, u' is about 800 and u'' is about 180.  The fact that 
mu is complex means that coupling between the windings will have phase 
shift! Not only that, but loss in the core is coupled into the winding 
as resistance, which, because it is magnetically coupled, is multiplied 
by the square of the turns.

Here's a link to the listing of all their materials, with links to 
corresponding data sheets for each.

http://www.fair-rite.com/newfair/materials.htm

73, Jim K9YC