2. Introduction to coupled line theory

Two conductors parallel to a metal plane or contained in a cylindrical shield form two coupled transmission lines. If we return to the first configuration and assume that the distance between the conductors is comparable to their distance from the metal plane, we create two single-wire lines mutually influenced by an electric field and a magnetic field. It will be shown that the phenomena of electromagnetic coupling between lines profoundly modify the theoretical formalism and consequently the properties of signal propagation. Thus, in the progression of this second paragraph, the text will endeavor to extend the theories and properties elaborated in