Analysis and Simulation of a Novel UWB Bandpass Filter with Sharp Roll-Off, Compact Size and Wide Upper Stopband based on a Multiple-Mode Resonator

In this paper، a novel microstrip-line ultra-wideband (UWB) bandpass filter (BPF) based on multiple-mode resonator (MMR) is designed، analyzed and simulated. The structure of the proposed MMR constructed by a modified triple-mode stepped-impedance resonator (MSIR) loaded with a folded step-impedance stub (FSIS). This stub-loaded resonator could generate two more resonate modes and two transmission zeros (TZs) simultaneously. Proposed MMR’s dimensions properly tuned so that first five resonate modes of the proposed MMR roughly allocated in the desirable bandpass، i. e. 3. 1-10. 6GHz، as well as two TZs at the edge of the passband، leading to sharp roll-off. Finally، with using aperture-backed interdigital-coupled lines for feeding، an UWB BPF with compact size، high selectivity، good performance in-band، and wide stopbands is obtained. Simulation results are in excellent agreement with UWB BPF ideal case.