Impedance curves of a composite cable

The balancing of a composite submarine telegraph cable, that is, one composed of both loaded and unloaded sections, requires a knowledge of its terminal impedance characteristics. In this article the impedance of such a cable is shown to be similar to that of an “equivalent” unloaded cable. Because of its limited frequency range, however, the type of network used with the unloaded cable at low speed signalling cannot furnish a satisfactory balance at the higher speeds of which the composite cable is capable; it is predicted that the mathematical theory developed here will aid in devising a means of extending that range.