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Author

J.X. Liao

Bio: J.X. Liao is an academic researcher from University of Electronic Science and Technology of China. The author has contributed to research in topics: Band-pass filter & Stopband. The author has an hindex of 7, co-authored 16 publications receiving 151 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a multilayer substrate integrated waveguide (SIW) filter with an improved stopband using mixed coupled modified trisections (MCMTs) is presented.
Abstract: A novel multilayer substrate integrated waveguide (SIW) filter with an improved stopband using mixed coupled modified trisections (MCMTs) is presented. The proposed filter is composed of two cascade MCMTs embedded in LTCC substrate. Four transmission zeros (TZs) can be generated with only three resonators, where two TZs near the passband are utilised to achieve sharper skirt selectivity, and another two TZs for the upper wide stopand. A 10 GHz experimental filter has been designed, fabricated and measured to validate the proposed method.

44 citations

Journal ArticleDOI
TL;DR: In this article, a novel substrate integrated waveguide (SIW) hexagonal resonator structure and its applications to bandpass filters are presented based on the SIW techniques, the resonance characteristic of proposed resonator is investigated.
Abstract: A novel substrate integrated waveguide (SIW) hexagonal resonator structure and its applications to bandpass filters are presented. Based on the SIW techniques, the resonance characteristic of proposed resonator is investigated. The hexagonal SIW resonators, which can combine flexibility of rectangular cavities and performance of circular cavities, are convenient for bandpass filters design. Since any of the six sides of a hexagonal resonator can be utilized for coupling, the filter configurations are flexible and adaptable. By changing the coupling sides of the hexagonal resonators, two types of experimental circuit configuration at the same central frequency of 10 GHz but with different fractional bandwidths of 3 and 6%, including third-order Chebyshev and crossed-coupling trisection, are constructed, fabricated, and measured. Measured results show a good agreement with simulated ones and validate the proposed configurations.

32 citations

Journal ArticleDOI
TL;DR: In this article, a compact dual-band bandpass filter with an improved stopband using short-circuit centred stepped impedance resonators (SCSIRs) is presented.
Abstract: A compact dual-band bandpass filter with an improved stopband using short-circuit centred stepped impedance resonators (SCSIRs) is presented. The proposed filter consists of two SCSIRs, one of which is embedded in the other one to obtain two passbands. Multiple transmission zeros can be generated by the proposed SCSIR for high passband selectivity and upper wide stopband bandwidth. The centre frequencies and bandwidths of the two passbands can be controlled by adjusting the geometric dimensions of the SCSIRs, respectively. A 2.4/5.2 GHz dual-band experimental BPF has been designed and fabricated to demonstrate the proposed method.

22 citations

Journal ArticleDOI
TL;DR: In this article, a double-grating rectangular waveguide is used as the slow wave structure (SWS) for high power Ka-band electron beam backward wave oscillator, in which a high power sheet beam is used with a cross section of 30 mm.
Abstract: It is attractive to use sheet beam vacuum devices to generate high frequency, high-power microwave radiation. In this paper, we present the numerical and experimental studies of a high-power Ka-band sheet electron beam backward wave oscillator (BWO), in which the double-grating rectangular waveguide is used as the slow wave structure (SWS) for its thermal and mechanical robustness. The fundamental mode of this kind of SWS is an antisymmetric mode which has an antisymmetric longitudinal field distribution and will nonsynchronously interact with the electron beam on two sides of the electron channel along the vertical direction. We put forward a method to overcome this trouble in this paper. To drive this BWO, a high-power sheet beam is used with a cross section of 30 mm $\times\,$ 1 mm. A thin graphite cathode is used for its superiority in producing a high current, high-quality electron beam. For an experimental electron beam of 141 kV and 1668 A, the output power of over 46.8 MW at 31.68 GHz is obtained, which corresponds to a beam–wave interaction efficiency of 19.9%. Compared with the conventional hollow beam BWO and the single-grating rectangular waveguide sheet beam BWO, the double-grating sheet beam BWOs efficiency is higher, which indicates that the double-grating sheet beam device is promising for producing millimeter wave radiation with high power and high efficiency.

15 citations

Journal ArticleDOI
TL;DR: In this paper, a 140 GHz folded-waveguide traveling wave tube (FWG-TWT) with a relatively larger circular electron beam tunnel was designed and developed using simulation software, the high frequency characteristics, the transfer characteristics, and the beam-wave interaction of the TWT were studied in detail.
Abstract: A 140-GHz folded-waveguide traveling wave tube (FWG-TWT) with a relatively larger circular electron beam tunnel was designed and developed. Using simulation software, the high frequency characteristics, the transfer characteristics, and the beam-wave interaction of the TWT were studied in detail. The simulation predicted up to 98 W output power and about 43 dB gain of FWG-TWT at the center frequency. The input and output couplers compatible with the FWG-SWS and the periodic permanent magnet focusing structure were designed. The FWG-TWT thus designed was fabricated and tested. The experimental result shows the output power exceeding 1.6 W and the gain exceeding 25 dB at 140 GHz when the input power is 5 mW. The reasons for the departure of the experimental from the simulated results have been explained.

12 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this article, an open stub-loaded shorted stepped-impedance resonator (OSLSSIR) with two identical open stubs loaded at its impedance junctions is proposed.
Abstract: This paper presents a new class of dual-, tri- and quad-band BPF by using proposed open stub-loaded shorted stepped-impedance resonator (OSLSSIR). The OSLSSIR consists of a two-end-shorted three-section stepped-impedance resistor (SIR) with two identical open stubs loaded at its impedance junctions. Two 50- Ω tapped lines are directly connected to two shorted sections of the SIR to serve as I/O ports. As the electrical lengths of two identical open stubs increase, many more transmission poles (TPs) and transmission zeros (TZs) can be shifted or excited within the interested frequency range. The TZs introduced by open stubs divide the TPs into multiple groups, which can be applied to design a multiple-band bandpass filter (BPF). In order to increase many more design freedoms for tuning filter performance, a high-impedance open stub and the narrow/broad side coupling are introduced as perturbations in all filters design, which can tune the even- and odd-mode TPs separately. In addition, two branches of I/O coupling and open stub-loaded shorted microstrip line are employed in tri- and quad-band BPF design. As examples, two dual-wideband BPFs, one tri-band BPF, and one quad-band BPF have been successfully developed. The fabricated four BPFs have merits of compact sizes, low insertion losses, and high band-to-band isolations. The measured results are in good agreement with the full-wave simulated results.

131 citations

Journal ArticleDOI
TL;DR: In this paper, traveling wave tubes are rapidly evolving to provide unprecedented power level in comparison to solid state devices in the millimeter wave region of the spectrum (80-300 GHz) thus enabling a wide range of applications.
Abstract: Traveling wave tubes are rapidly evolving to provide unprecedented power level in comparison to solid state devices in the millimeter waves region of the spectrum (80–300 GHz) thus enabling a wide ...

75 citations

Journal ArticleDOI
TL;DR: In this article, a low-temperature co-fired ceramic (LTCC) bandpass filter with wide stopband and high selectivity was proposed, which consists of two coupled λg/4 transmission-line resonators.
Abstract: This paper presents a novel compact low-temperature cofired ceramic (LTCC) bandpass filter (BPF) with wide stopband and high selectivity. The proposed circuit consists of two coupled λg/4 transmission-line resonators. A special coupling region is selected to realize a novel discriminating coupling scheme for generating a transmission zero (TZ) at the third harmonic frequency. The mechanism is analyzed and the design guideline is described. The source-load coupling is introduced to generate two TZs near the passband and one in the stopband. Thus, wide stopband can be obtained without extra circuits. Due to the LTCC multilayer structures, the filter size is 0.058 λg×0.058 λg×0.011 λg, or 2.63 mm × 2.61 mm × 0.5 mm. The simulated and measured results of the demonstrated LTCC BPF are presented to validate the proposed design.

49 citations

Journal ArticleDOI
Xiang Wang1, Xiao-Wei Zhu1, Zhi Hao Jiang1, Zhang-Cheng Hao1, Yi-Wen Wu1, Wei Hong1 
TL;DR: In this paper, two different coupling topologies, electric coupling and magnetic coupling, are employed between two EMSIW resonant cavities, which are analyzed theoretically via the response of the structure and the relationship between the cavities.
Abstract: In this paper, a systematic research campaign on eighth-mode substrate integrated waveguide (EMSIW) filters is reported. The sizes of these EMSIW resonant cavities are only one-eighth or one-sixteenth of a conventional SIW resonant cavity. Two different coupling topologies, i.e., electric coupling and magnetic coupling, are employed between two EMSIW resonant cavities, which are analyzed theoretically via the response of the structure and the relationship between the cavities. Both coupling topologies enable structural variations that possess advantages and flexibility of the second-order EMSIW bandpass filters (BPFs) designing. By utilizing these basic coupling mechanisms, multilayer board technology, and other practical techniques, a class of triple-order SIW BPFs with the merits of compact size and high selectivity are demonstrated. Specifically, several triple-order EMSIW BPFs composed of pure EMSIW cavities or comprised by combining EMSIW and quarter-mode SIW cavities are simulated, fabricated, and measured for verification.

44 citations

Journal ArticleDOI
TL;DR: In this article, a mixed quarter and one-eighth modes substrate integrated waveguide (SIW) bandpass filter (BPF) is proposed to provide wide stopband response and high selectivity characteristics by using different SIW cavities.
Abstract: This letter presents the design of mixed quarter- and one-eighth modes substrate integrated waveguide (SIW) bandpass filter (BPF). The transmission zeros (TZs) of the proposed SIW BPF can provide wide stopband response and high selectivity characteristics by using different mode SIW cavities. For validation, two- and three-stage SIW BPFs with Chebyshev response were designed at a center frequency ( $f_{0}$ ) of 8 GHz. The measured results are consistent with the simulations. For two-stage BPF, the insertion loss smaller than 0.9 dB is measured within the passband of 0.65 GHz (7.75–8.4 GHz). The return loss higher than 19.7 dB is measured within the same passband. The spurious is produced at around 18 GHz ( $ ). The stopbands are attenuated more than 17.31 dB from the dc to 5.68 GHz ( $0.71f_{0}$ ) and from 9.28 GHz ( $1.16f_{0}$ ) to 16.67 GHz ( $2.08f_{0}$ ). The TZs are produced at 10 GHz and around 18 GHz due to a small cross-coupling between source/load and the interaction of the higher resonant modes of cavities, respectively. For three-stage BPF, the $\vert S_{21}\vert $ and $\vert S_{11}\vert $ smaller than −1.3 dB and −18 dB are measured within the passband of 7.57–8.45 GHz fractional bandwidth (FBW = 11%), respectively. The TZs are produced at 1.102, 1.9, and $2.39f_{0}$ and provide higher selectivity and attenuation compared to two-stage BPF.

41 citations