The mathematical theory of wave propagation along a conductor with an external coaxial return is very old, going back to the work of Rayleigh, Heaviside, and J. J. Thomson. These words were written by S. A. Schelkunoff back in 1934. Indeed, those early works dealt with signal propagation along the line as well as electromagnetic shielding of the environment inside and/or outside the metallic enclosures. Max well himself developed pioneering studies of single-layer shielding shells, while a paper with such a "modern" title as "On the Magnetic Shielding of Concentric Spherical Shells" was presented by A. W Rucker as early as 1893! * Such "state of the art" shielding theory created in the last century is even more amazing if you think that at almost the same time (namely, in 1860s), a manuscript of Jules Verne''s book, Paris in the. xx Century, was rejected by a publisher because it pre dicted such "outrageously incredible" electrotechnology as, for example, FAX service by wires and the electrocutioner''s chair. (With regard to the last invention, I suspect many readers would rather Jules Verne has been wrong. ) However, although the beginning of electromagnetic shielding theory and its implementation to electronic cables date back more than a century, this dynamic field keeps constantly growing, driven by practical applications.
