High-frequency coaxial cables

It is shown that simple transmission-line theory leads to agreement with Millington and radical conflict with Barlow concerning the effect of dielectric layers on the conducting walls of a high-frequency coaxial cable. Suggestions are given of possible sources of error in Barlow's analysis of the power-flow method, and mention is made of the Riccati equation satisfied by the ratio Ex/H?, with an approximate solution agreeing with Millington's results. The experimental values of attenuation reported by Barlow and Sen are therefore, as yet, unexplained theoretically.