New directions in gain-bandwidth theory and broad-band matching

The problem of broad-band matching is that of realizing a prescribed gain function between a generator and a load (not both resistive), by means of a purely reactive equalizer. The authors present a comprehensive survey of the status of the art. The authors compare the solutions of the classical broad-band matching problem provided by the analytic theory, the function space theory, the real frequency technique and the partially Fourier technique. The authors mention some extensions. It is shown that they all bear upon the function concept that the compatibility between a gain function and a given load can be expressed in terms of causability. The authors compare the performances of the various approaches from both a theoretical and an engineering point of view