A simple formula for calculating the frequency‐dependent resistance of a round wire

At high frequencies, the current distribution across a circular wire is 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 inoles determining complex Bessel func- tions, the solution of which is prone to approximations as the skin depth becomes less than about one tenth the wire radius. An alternatie method of determining this resistance is presented which is significantly simpler than the Bessel function approach, easier toisualize, and not reliant on approximations when determining the solution. This approach is based on determining the width of an annulus which carriers the equialent current to the full wire. Results are presented which confirm the accuracy of the equialent annulus method. Q 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 84)87, 1998.