Compact tri‐wideband bandpass filter with multiple transmission zeros

Abstract

This paper presents a tri‐wideband bandpass filter (TWB‐BPF) with compact size, high band‐to‐band isolation, and multiple transmission zeros (TZs). The proposed TWB‐BPF is based on a multiple‐mode resonator (MMR), which is interpreted by the method of the even‐ and odd‐mode analysis technique. The MMR can excite 11 resonant modes, where the first two modes comprise the first passband, the next four modes form the second passband, and the last five modes are used to generate the third passband. In addition, 10 TZs are yielded to obtain high band‐to‐band isolation and wide stopband suppression characteristics up to 14.95fc1 (fc1 is the center frequency of the first passband). To verify the proposed filter, a TWB‐BPF with 3‐dB fractional bandwidths (FBWs) of 37.4%, 43.5%, and 40.4% is designed, fabricated, and measured.

Dual-/tri-band bandpass filters with fully independent and controllable passband based on multipath-embedded resonators

“…Therefore, high-performance multi-band BPFs have aroused wide concern. So far, various multi-band BPFs have been proposed to meet different applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. As a straightforward method, combining several individual resonators or BPFs with a careful arrangement is a practical approach to design multi-band BPFs [1,2], but it usually suffers from larger circuit dimensions.…”

“…However, DGS technology will increase the fabrication complexity, and it is difficult to integrate with planar circuits. For the merits of simple structure, multi-mode resonators (MMRs) are widely used to design multi-band BPFs [6][7][8][9][10]. However, mutual interferences between resonant modes are inevitable usually.…”