Compact tri‐band bandpass filter with controllable frequencies

et al. 2022

J. Phys.: Conf. Ser.

This article proposes a dual-band bandpass filter (BPF) based on stub-loaded resonator (SLR) with the second passband independently tunable. Varactors loaded on the end of the central stub are employed to independently tune the second passband. Two shunt quarter-wavelength open stubs and source-load (S-L) coupling are applied to generate transmission zeros (TZs) to enhance the selectivity and improve the out-band rejection. For verification, a tunable dual-band BPF is designed, fabricated and tested, which realizes frequency tuning range (FTR) of the second passband from 2.24 to 2.71 GHz with constant fractional bandwidth (CFBW) of 1.5±0.4%. The simulated and measured results are in good accordance.

Section: Introductionmentioning

confidence: 99%

A Dual-band Bandpass Filter with The Second Passband Independently Tunable

Yang

et al. 2022

J. Phys.: Conf. Ser.

“…In recent years, as the multifunctional wireless communication systems developed, a great demand for multi-band filters [1][2][3] has grown. A tunable filter with compactness, low insertion loss (IL), and high performance is a necessary component that meets multi-band requirements; thus, it has drawn great attention.…”

Section: Introductionmentioning

confidence: 99%

A highly selective tri‐band bandpass‐to‐bandstop filter with the third band independently tunable

Yang

et al. 2021

Engineering Reports

A highly selective tri-band bandpass (BP)-to-bandstop (BS) filter with the third tunable band and the other two fixed ones is proposed in this article. This filter is based on a novel crossed resonator that is composed of a two-end-open UIR with an open stub and a short stub connected in parallel on both sides of the resonator center. A PIN diode is utilized to achieve BP-to-BS switchable characteristics. Then, varactor diodes loaded at the open stub are employed to obtain the independently tunable third band. In addition, due to the symmetry of the resonator structure, the even-and odd-mode analysis method is used to derive the resonant frequencies. For validation, a tri-band BP-to-BS filter operating at 2.4 GHz (WLAN), 3.3 GHz (WiMAX), and 4.9 GHz (LAA/LTE-U) is designed, manufactured, and measured that achieves the continuous frequency tuning range (FTR) of the third band from 4.52 to 4.90 GHz with return loss (RL) better than 10.05 dB under the BP characteristic, from 4.55 to 4.90 GHz with the rejection level (RL) higher than 15.53 dB under the BS characteristic. The measured results agree well with the simulated ones.

“…Due to the merits of planar structure such as low cost, small size and easy fabrication, a lot of research studies have been done to design multiband microstrip filters. Among them, stepped‐impedance resonators (SIRs), stub‐loaded resonators (SLRs), and other multimode resonators (MMRs) are widely used in the design of multiband filters with compact size 1‐13 …”

Section: Introductionmentioning

confidence: 99%

“…In Reference 4, two‐mode SLR is incorporated inside of the open‐loop resonator as an internal resonator, which can realize high selectivity and compact size, while only the CF of the third passband can be tuned flexibly. In Reference 5 a novel resonator loaded with two stubs is proposed to constitute a tri‐band filter, the CFs of the first and third passbands can be adjusted, while the BWs of the three passbands cannot be arbitrarily designed. Apart from that, a new class of double‐stub‐loaded UIRs known as cross resonators which were initially proposed in Reference 6 became popular.…”

Section: Introductionmentioning

confidence: 99%

“…Among them, stepped-impedance resonators (SIRs), stub-loaded resonators (SLRs), and other multimode resonators (MMRs) are widely used in the design of multiband filters with compact size. [1][2][3][4][5][6][7][8][9][10][11][12][13] In References 1-3, a set of dual-/tri-/quad-band filters using SIRs and its improved structures, that is, λ/2 type SIRs assembled with UIR, 1 tri-sections SIRs 2 and asymmetric SIRs 3 are proposed. To further control the center frequencies (CFs) and bandwidths (BWs) of each passband, stubs are loaded to enhance the advantages of SIRs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tri‐band superconducting filter based on crossed resonators with controllable coupling and feeding structures

Liu

Int J RF Microw Comput Aided Eng

et al. 2020

In this article, a compact tri-band high-temperature superconducting filter with controllable coupling and feeding structures based on crossed resonator which consists of two-end-open UIR with a short stub and an open stub shunted at the resonator center is proposed. Due to the symmetrical structure of the proposed resonator, the odd-and even-mode analysis method can be used to derive their resonance frequencies. Then, a capacitance-loaded microstrip line is added between the resonators to flexibly control the bandwidths. Furthermore, one tapped line and one coupled line are utilized to realize the acquired external coupling under prior specifications. For demonstration, a tri-band filter operating at 1.6 GHz (Global Positioning System), 2.45 GHz (Wireless Local Area Networks), and 3.5 GHz (WiMAX) is designed, analyzed using the electromagnetic simulator, and fabricated using an YBa 2 Cu 3 O y thin film on an MgO substrate. The measured results agree well with the simulated ones.