A WIDEBAND QUASI-MILLIMETER-WAVE BANDPASS FILTER USING DUAL-MODE RESONATOR WITH 5/4 WAVELENGTH FOLDED STUBS

摘要

A novel wideband quasi-millimeter-wave filter with good in-band and out-band performances is proposed in this article. A dual-mode square ring resonator loaded with two 5λ{sub}0/4 (λ{sub}0 is the center wavelength of the filter) folded stubs is introduced to realize a 3 dB passband bandwidth of about 15%. Because of the transmission zeros produced by the dual-mode ring resonator in the stopbands, the proposed filter exhibits sharp attenuations near the passband. On the other hand, a parallel-coupled two-mode resonator is introduced and integrated with the dual-mode ring resonator to get a further improvement of the out-band performance with wide stopbands. The fabricated filter has an insertion loss better than 2 dB in the passband and rejections greater than 20 dB at most of the frequencies in the stopbands.