Invention of Pupin’s periodically distributed inductance coils to allow for long-distance telephone transmission

Pupinpsilas theory of periodically loaded telephone lines, allowing for significant reduction of attenuation within the baseband telephone signal transmission, and its experimental verification are presented in this paper. Such so-called Pupin loading was achieved by the use of discrete inductance coils of toroidal form equally distributed along the line. In addition, a modern full wave matrix approach of such Pupinized transmission line is used in order to further illustrate the effects of Pupinpsilas coils inclusion on line transmission characteristics and bandwidth. For that purposes, so-called Heaviside criterion fulfilment factor is introduced and comparison with unloaded line and equivalent uniform line characteristics is presented.