Coaxial-Line Pulse-Response Error Due to a Planar Skin-Effect Approximation

The time-domain error introduced by the planar skin-effect approximation is examined by comparing the approximate response with the cylindrical skin-effect response. Expressions are developed for the cylindrical skin-effect response and applied to line outer conductor ID sizes ranging from a 0.1-mm microminiature size to 10 mm. For 50-air dielectric lines (including 3.5 and 7 mm) curves are given for the cylindrical skin-effect response transition (rise) time (0 to 50 percent and 10 to 90 percent) versus line length (0.01-100 m). Step responses are given for a 1-m length of 0.1-mm 50-¿ microminiature line with relative dielectric constants of 1, 2, and 3.