[Lowfer] LitZ Wire Reference Paper

[Bill Ashlock]

With all due respect to the Dartmouth Engineering Department (from which I 
can proudly say my daughter graduated from last year) the author has a way 
of failing to get to chase of the Litz Vs solid wire comparison.

If Litz wire has sufficiently small individual insulated wires (#38 or 
smaller for the Lowfer band) the AC resistance, according to the math, works 
out to be 1/2 the AC resistance for the same diameter solid copper wire. 
Using #12 wire as a base line reference the AC resistance is 1.2 ohms per 
200ft (note the influence of loop antennas, here). The AC resistance for 200 
ft of #12 litz would be 0.6 ohms. The size of solid conductor equivalent to 
#12 litz would have to be 2X the diameter (not 2x the area) or #6. (Loop 
enthusists: note the weight would increase from 4 to 16 lbs/200ft!)

The skin depth (the mathematical thickness that defines where 100% of the 
current in the conductor flows) does not change with conductor size at this 
frequency. Therefore a conductor at AC can be thought of as a cylinder 
having the same OD as the OD of the actual conductor, and a shell thickness 
of the skin depth. The area where current flows is proportional the diameter 
of the wire, hence the AC resistance is also proportional to the diameter of 
the wire.

Bill A



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