Direct synthesis of transmission-line elliptic bandpass filters

Summary form only given, as follows. A direct synthesis method of elliptic function transmission-line filters is presented in this paper. The filter designs start from elliptic lumped prototype filters, and then Richards´ transform is applied to obtain commensurate transmission-line circuits. Two coupled-line structures and their equivalent circuits are introduced, and they can be assembled to realize the elliptic filters. An example of fifth-order elliptic filter is given and has shown the feasibility of the design procedure.