A Microstrip SIR Dual-Mode Bandpass Filter with Simultaneous Size Reduction and Spurious Responses Suppression

Abstract

A novel miniaturized microstrip dual-mode bandpass filter with simultaneous size reduction and spurious responses suppression is proposed. In this new filter structure, the stepped-impedance resonator (SIR) technique is used to not only shorten the resonator size but also suppress its spurious responses. A prototype dual-mode bandpass filter centered at 1.6 GHz with 3% FBW is designed and experimentally characterized. This new filter achieves 33% size diminution when compared with the conventional structure. In addition, spurious responses at 2f0 and 3f0 are suppressed by 20 dB and 18 dB respectively.