Design of a dual‐band bandpass filter with a wide stopband

Abstract

A novel wide-stopband dual-band bandpass filter with a modified coupled line and lowpass filters is proposed. The modified coupled line is realised with two open stubs added to the conventional coupled line's open ends. With this proposed circuit, additional transmission zeros will appear around two passbands. Moreover, these predictable transmission zeros can be utilised to tune the two passbands' bandwidths. Furthermore, with the lowpass filter embedded, located at the input/output port, a wide stopband can be obtained. Finally, agreement between measurement and the theoretical prediction validates the proposed structure.

Compact dual- and triband bandpass filter using frequency selecting coupling structure loaded stepped-impedance resonator

“…Using asymmetric SIR and stub loaded coupled line , two dual‐band BPFs with greater than 20 GHz stopband are reported. However, the external input/output impedance transformation feeding lines in and lowpass filter structures in are introduced to improve the filter performance, which result in the large filter area. A compact dual‐band BPF based on T‐shaped dual‐mode resonator is proposed in .…”

Coupled‐line dual‐band bandpass filter with compact structure and wide stopband

“…To improve the insertion loss of dual-band bandpass filters, a hightemperature superconducting filter has been researched in [4]. Furthermore, the wide stopband performance of dual-band bandpass filters has been reported in [5][6][7]. However, the proposed bandpass-filter structures in [5,6] require large-size circuits, whereas the operating dual-band bandwidths of the filter in [7] are very narrow.…”