A SIMPLE FORMULA FOR CALCULATING THE FREQUENCY-DEPENDENT RESISTANCE OF A ROUND WIRE

At high frequencies, the current distribution across a circular wire i s modified by the skin effect, causing the greatest current density to be near the surface of the wire. One common method of calculating the wire resistance involves determining complex Bessel functions, the so lution of which is prone to approximations as the skin depth becomes l ess than about one tenth the wire radius. An alternative method of det ermining this resistance is presented which is significantly simpler t han the Bessel function approach, easier to visualize, and not reliant on approximations when determining the solution. This approach is bas ed on determining the width of an annulus which carriers the equivalen t current to the full wire. Results are presented which confirm the ac curacy of the equivalent annulus method. (C) 1998 John Wiley & Sons, I nc.