ABSTRACT
Finite conductivity in a coaxial line limits the current density to finite values and thereby causes it to be distributed continuously over the cross section of each conductor rather than concentrated on the surface closest to the other conductor. In the study of conductor resistance as a function of frequency, the spectrum may logically be divided into two ranges of distinctly different behavior. These might be called, the range of negligible skin effect and the range of pronounced skin effect. A similar plot may be anticipated for the sum of the resistances of the conductors in a coaxial cable or an open-wire line. Skin-effect-demarcation frequency, fskd, is suggested as a name for the frequency corresponding to the intersection of the high-frequency asymptote with the direct-current-resistance ordinate. For usual telephone lines, voice-frequency transmission is largely in the range below the skin-effect-demarcation frequency, whereas carrier-frequency transmission is primarily in the range above that frequency.
