The synthesis of a class of lossy distributed networks

A class of filter networks that consists of sections of microstrip transmission lines employing a semiconductor dielectric operating between resistive terminations is investigated. It is shown that the transfer functions of this class of lossy networks can be expressed in the same form as corresponding functions for lossless structures, thus making feasible the application of methods of synthesis already available for lossless structures. A design procedure is presented for the systematic synthesis of this class of networks. The procedure is illustrated by several design examples including both maximally flat magnitude and Chebyshev bandpass filters. Two filters were fabricated using microstrip sections containing a high-loss silicon dielectric. The measured and calculated responses of both filters were in good agreement.