Nowadays, the speed of electronic signals is growing rapidly due to market requirements and to progress in technology, e.g. allowing switching times below 1 ns. Because of such high speed signals the distance between the wires of interconnects existing at various levels in an electronic circuit may become comparable with the smallest characteristic wavelength of the signal themselves. As a consequence high frequency effects such as dispersion and radiation losses are no more negligible and there is the need of a new model to describe the propagation of the signals along the interconnects. The Enhanced Transmission Line (ETL) model, showed in this book, allows to forecast phenomena that the Standard Transmission Line (STL) cannot foresee, such as the distortion introduced by the non-local nature of the electromagnetic interaction along the conductors, and the attenuation due to radiation losses in the transverse direction.