Design of compact and high selectivity TRI‐band wideband microstrip BPF

Abstract

In this article, a novel tri‐band wideband microstrip bandpass filter (BPF) with compact size and high selectivity is proposed using three sets of resonators, that is, λ/4 resonators, short‐stub loaded resonator, and λ/2 resonators.Each of the resonators can not only separately generate one passband, but also mainly control the passband performance. Due to the extended feed lines, parasitic coupling and intrinsic characteristics of the resonators, multiple transmission zeros can be created to improve the selectivity. A tri‐band wideband microstrip BPF centered at 2.0, 3.6, and 5.5 GHz is designed, and the predicted results are confirmed experimentally. The size is only 0.156 × 0.303 λg in which λg is the guided wavelength at 2.0 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:258–261, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27334

Compact tri‐wideband bandpass filter with multiple transmission zeros

“…and Z n (n = 1, 2, 3, 4, 5, and 6) denote the characteristic impedance. Therefore, the resonant frequencies can be solved numerically based on (6) and (7).…”

“…In recent years, multi-band bandpass filters (BPFs) have attracted much interest. For example, various excellent works that focused mainly on multi-band and high selectivity have been reported [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In [1][2][3][4][5], stepimpedance resonators are widely employed to design dualband, tri-band, and quad-band BPFs.…”

“…In [1][2][3][4][5], stepimpedance resonators are widely employed to design dualband, tri-band, and quad-band BPFs. The method of combining several BPFs or resonators with common input/output ports is a straightforward and effective approach to design multi-band BPFs [6][7][8][9]. Using this approach, singleband, dual-band, tri-band, quad-band, and quint-band BPFs can be easily achieved [6].…”

Planar dual‐ and tri‐band bandpass filters using single improved ring resonator and simple feed scheme

“…To meet the increasing communication requirement, many modern wireless communication systems have been fast developed and widely used in people's daily life, such as wireless local area network (WLAN), IEEE 802.16 worldwide interoperability for microwave access (WiMAX), radio‐frequency identification (RFID) and so on. Therefore, developments in microwave multiband bandpass filters (BPFs) have been gaining much attention for the increasing applications of multiband wireless communication systems, and a variety of methods have been proposed recently to design multiband BPFs . The stub‐loaded resonators (SLRs), which can be analyzed by the odd‐ and even‐mode method, are widely used to design dual‐ and tri‐band filters .…”

Design of Novel Compact Tri-Band Bandpass Filter With Controllable Frequencies and High Selectivity

“…However, it occupies large area. To reduce the size, one set of resonators is embedded in the other set of resonators is proposed [14,15]. Besides the above methods, stub-loaded resonator combined with embedded multisets of resonators also can be employed [16,17].…”