A new design procedure of tapped coupled-line filters

In this paper, a new design method for tapped coupled-line filters is presented. The proposed design method is based on the equivalent circuit models for a tapped-line and a coupled-line. Since the tapped-line filter replaces input and output coupled lines of the edge coupled filter, which tend to have very narrow gaps (few mils), it has the advantage of less sensitivity to fabrication tolerances. The performance of the designed tapped-line filter is very similar to that of the edge-coupled filter. The designed tapped-line filter performed well up to 20 GHz with slight parameter modifications.