Design of even-order dual-behavior resonators bandpass filter

In this paper, a simple method to design even-order dual-behaviour resonators (DBR) filters is proposed. First, by implementing admittance inverters, the conventional asymmetrical prototype is transformed into a new symmetrical prototype; also, the source and load resistances are equal. Second, a new analytical method for DBR to extract equivalent circuit parameter is proposed. Finally, a bandpass filter with center frequencies of 3.3 GHz is designed, which only consists of series lambda _g/4 transmission line inverters and DBR based upon parallel different length stubs. The experimental results validate the proposed theory.