Synthesis of broadband filters with dual-mode stepped impedance resonators

In this paper, the redundant synthesis of BPFs with dual-mode stepped impedance resonators is studied. Network models of both the dual-mode resonator BPFs and the conventional parallel coupled-line BPFs are shown to be equivalent. Redundant design procedure is proposed to design the second-order BPFs and design equations are derived, based on approximate design procedure. Design example is given to help justify the proposed design method. It is found that filters using dual-mode resonators are easier to realize than conventional parallel coupled-line filters for broadband applications.