We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transiti...We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO_2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain(FITD) method and finite element method(FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process,and characterized by a THz time-domain-spectrometer(TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.展开更多
Solar-blind ultraviolet (UV) band-pass filter has significant value in many scientific, commercial, and military appli- cations, in which the detection of weak UV signal against a strong background of solar radiatio...Solar-blind ultraviolet (UV) band-pass filter has significant value in many scientific, commercial, and military appli- cations, in which the detection of weak UV signal against a strong background of solar radiation is required. In this work, a solar-blind filter is designed based on the concept of "transparent metal". The filter consisting of Al/SiO2 multilayers could exhibit a high transmission in the solar-blind wavelength region and a wide stopband extending from near-ultraviolet to infrared wavelength range. The central wavelength, bandwidth, Q factor, and rejection ratio of the passband are numerically studied as a function of individual layer thickness and multilayer period.展开更多
A dual-band terahertz(THz) filter consisting of two different cross slots is designed and fabricated in a single molybdenum layer. Experimental verification by THz time-domain spectroscopy indicates good agreement w...A dual-band terahertz(THz) filter consisting of two different cross slots is designed and fabricated in a single molybdenum layer. Experimental verification by THz time-domain spectroscopy indicates good agreement with the simulation results. Owing to the weak coupling between the two neighboring cross slots in the unit cell, good selectivity performance can be easily achieved, both in the lower and higher bands, by tuning the dimensions of the two crosses. The physical mechanisms of the dual-band resonant are clarified by using three differently configured filters and electric field distribution diagrams. Owing to the rotational symmetry of the cross-shaped filter, the radiation at normal incidence is insensitive to polarization. Compared with the THz dual-band filters that were reported earlier, these filters also have the advantages of easy fabrication and low cost, which would find applications in dual-band sensors, THz communication systems, and emerging THz technologies.展开更多
This paper presents a planar microstrip wideband dual mode Band-Pass Filter(BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz.The dual mode band-pass filter consists of a ring resonator with two quarter-wavel...This paper presents a planar microstrip wideband dual mode Band-Pass Filter(BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz.The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at =90o and =0o,respectively.A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity.By using a parallel-coupled feed line,a narrow notched band is introduced at the required frequency and its Fractional BandWidth(FBW) is about 5%.The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic,the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz(cal-culated from 1.959 GHz with-34.43 dB to 2.065 GHz with-2.93 dB) and 228.10 dB/GHz(calculated from 3.395 GHz with-2.873 dB to 3.507 GHz with-28.42 dB).This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz.Having been presented in this article,the measurement results agree well with the simulation results,which validates our idea.展开更多
This paper reports the use of the fast Fourier transform (FFT) in the direct Fourier transform method (DFM) in Computerized Tomography (CT) reconstruction. Phase corrections are needed in the CT reconstruction. In ord...This paper reports the use of the fast Fourier transform (FFT) in the direct Fourier transform method (DFM) in Computerized Tomography (CT) reconstruction. Phase corrections are needed in the CT reconstruction. In order to eliminate the image distortion from the basic DFM, Padding and band-pass filters are used in the improved DFM. Finally, some reconstructions from simulated projections and several experimental results are given.展开更多
This study presents two multimode stepped-impedance structures to design single-and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The...This study presents two multimode stepped-impedance structures to design single-and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth (FBW) of 25.6%. Four stubs (two low frequency and two high frequency ones) are connected to the rectangular patch in the center to construct a quadruple-mode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single-and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.展开更多
We have designed and proposed the edge modes supported by graphene ribbons and the planar band-pass filter consist- ing of graphene ribbons coupled to a graphene ring resonator by using the finite-difference time-doma...We have designed and proposed the edge modes supported by graphene ribbons and the planar band-pass filter consist- ing of graphene ribbons coupled to a graphene ring resonator by using the finite-difference time-domain numerical method. Simulation results show that the edge modes improve the electromagnetic coupling between devices. This structure works as a novel, tunable mid-infrared band-pass filter. Our studies will benefit the fabrication of planar, ultra-compact nano-scale devices in the mid-infrared region. A power splitter consisting of two output ribbons that is useful in photonic integrated devices and circuits is also designed and simulated. These devices are useful for designing ultra-compact planar devices in photonic integrated circuits.展开更多
An Electromagnetic Band Gap (EBG) loaded square waveguide Band-Pass Filter (BPF) is proposed in this paper. It’s simply composed by symmetrically loading periodical metal diaphragms on each wall of a square waveguide...An Electromagnetic Band Gap (EBG) loaded square waveguide Band-Pass Filter (BPF) is proposed in this paper. It’s simply composed by symmetrically loading periodical metal diaphragms on each wall of a square waveguide. The influences of insert sizes and loading periods on the overall BPF performances are analyzed. Experimental results agree well with those predicted. 6 GHz pass-band with insert loss less than 1 dB, 2.5 GHz stop-band and larger than 25 dB polarization isolation can be obtained. The BPF can be applied in dual-polarized waveguide-based antenna-feed systems.展开更多
A terahertz(THz) waveguide band-pass filter using an iris inductive window coupled structure was designed and fabricated.The filter was designed at0.22 THz with a pass band of 20 GHz.The measured results show that t...A terahertz(THz) waveguide band-pass filter using an iris inductive window coupled structure was designed and fabricated.The filter was designed at0.22 THz with a pass band of 20 GHz.The measured results show that the center frequency is 0.218 THz with a pass band of 0.205 THz to 0.231 THz,the minimum insertion loss is 1.26 d B at 0.224 THz,and the return loss is less than 13.1 d B.The stop-band suppression is65.6 d B at 0.193 THz and 51.8 d B at 0.243 THz,respectively,which means a good performance of high stop-band suppression.A good agreement exists between the measured S-parameters and the simulated ones,especially in the upper band.The proposed THz waveguide filter has potential applications in THz communications.展开更多
The multilayer structure is a promising technique used to minimize the size of planar microstrip filters.In the flexible design and incorporation of other microwave components,multilayer band-pass filter results in be...The multilayer structure is a promising technique used to minimize the size of planar microstrip filters.In the flexible design and incorporation of other microwave components,multilayer band-pass filter results in better and enhanced dimensions.This paper introduces a microstrip fifth-generation(5G)low-frequency band of 2.52–2.65 GHz using a parallel-coupled line(PCL)Bandpass filter and multilayer(ML)hairpin Bandpass filter.The targeted four-pole resonator has a center frequency of 2.585 GHz with a bandwidth of 130 MHz.The filters are designed with a 0.1 dB passband ripple with a Chebyshev response.The hairpin-line offers compact filter design structures.Theoretically,they can be obtained by bending half-wavelength resonator resonators with parallel couplings into a“U”shape.The proposed configuration of the parllel-coupled line resonator is used to design the ML band-pass filter.The FR4 substrate with a dielectric constant(Er)of 4.3 and 1.6 mm thickness was used.A comparative analysis between the simulated insertion loss and the reflection cofficient of substrates RO3003 and FR4 was performed to validate the eficiency of the proposed filter design.Simulation of PCL filter is accom-plished using computer simulation technology(CST)and an advanced design system(ADS)software.The PCL Bandpass filter was experimentally validated and a total tally between simulation results and measured results were achieved demonstrating a well-measured reflection coefficient.The simulated results obtained by the hairpin ML bandpass filter show that the circuit performs well in terms of Scattering(S)parameters and the filter size is significantly reduced.展开更多
This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resona...This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resonator (SIR), however, it does not give analytical equations or prediction for the dual-resonance characteristics of the NPHR structure discussed in this paper. Consequently, a circuit model is proposed to analyze the dual-resonance characteristics of NPHRs. Analytical equations are derived, showing that the frequency ratio of a dual-band NPHR can be determined by the ratio of turns. EM simulation and experimental results have shown good agreement with the circuit analysis. The derived analytical equations from circuit model can be used for fast design of NPHRs. A step-width aperture is proposed to independently control the coupling coefficients at the each band of NPHRs. A third order dual-passband filter has been designed and fabricated. The filter has 3.3% and 3% fractional bandwidths at 789 MHz and 2402 MHz, respectively. The designed prototype filter shows that NPHRs can be utilized to realize compact filters with dual-band characteristics. The filter design can be extended from engineering perspective for application in wireless communication systems.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574059,61565004,and 11774288)the National Technology Major Special Project,China(Grant No.2017ZX02101007-003)+2 种基金the Natural Science Foundation of Guangxi,China(Grant Nos.2015GXNSFDA139039 and2017GXNSFBA198116)the Foundation from Guangxi Key Laboratory of Automatic Detection Technology and Instrument,China(Grant No.YQ16101)the Innovation of Guangxi Graduate Education,China(Grant Nos.2018YJCX70,2018YJCX67,and 2018YJCX74)
文摘We experimentally demonstrate an electrically triggered terahertz(THz) dual-band tunable band-pass filter based on Si_3 N_4–VO_2–Si_3 N_4 sandwich-structured hybrid metamaterials. The insulator–metal phase transition of VO_2 film is induced by the Joule thermal effect of the top metal layer. The finite-integration-time-domain(FITD) method and finite element method(FEM) are used for numerical simulations. The sample is fabricated using a surface micromachining process,and characterized by a THz time-domain-spectrometer(TDS). When the bias current is 0.225 A, the intensity modulation depths at two central frequencies of 0.56 THz and 0.91 THz are about 81.7% and 81.3%, respectively. This novel design can achieve dynamically electric–thermo–optic modulation in the THz region, and has potential applications in the fields of THz communications, imaging, sensing, and astronomy exploration.
基金supported by the National Basic Research Program of China(Grant Nos.2010CB327504,2011CB922100,and 2011CB301900)the National NaturalScience Foundation of China(Grant Nos.60936004 and 11104130)+1 种基金the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK2011556 andBK2011050)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Solar-blind ultraviolet (UV) band-pass filter has significant value in many scientific, commercial, and military appli- cations, in which the detection of weak UV signal against a strong background of solar radiation is required. In this work, a solar-blind filter is designed based on the concept of "transparent metal". The filter consisting of Al/SiO2 multilayers could exhibit a high transmission in the solar-blind wavelength region and a wide stopband extending from near-ultraviolet to infrared wavelength range. The central wavelength, bandwidth, Q factor, and rejection ratio of the passband are numerically studied as a function of individual layer thickness and multilayer period.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174280 and 61107030)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.YYYJ-1123)the China Postdoctoral Science Foundation(Grant No.2012M520377)
文摘A dual-band terahertz(THz) filter consisting of two different cross slots is designed and fabricated in a single molybdenum layer. Experimental verification by THz time-domain spectroscopy indicates good agreement with the simulation results. Owing to the weak coupling between the two neighboring cross slots in the unit cell, good selectivity performance can be easily achieved, both in the lower and higher bands, by tuning the dimensions of the two crosses. The physical mechanisms of the dual-band resonant are clarified by using three differently configured filters and electric field distribution diagrams. Owing to the rotational symmetry of the cross-shaped filter, the radiation at normal incidence is insensitive to polarization. Compared with the THz dual-band filters that were reported earlier, these filters also have the advantages of easy fabrication and low cost, which would find applications in dual-band sensors, THz communication systems, and emerging THz technologies.
基金Supported by the National Natural Science Foundation of China (No. 51007040)
文摘This paper presents a planar microstrip wideband dual mode Band-Pass Filter(BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz.The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at =90o and =0o,respectively.A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity.By using a parallel-coupled feed line,a narrow notched band is introduced at the required frequency and its Fractional BandWidth(FBW) is about 5%.The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic,the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz(cal-culated from 1.959 GHz with-34.43 dB to 2.065 GHz with-2.93 dB) and 228.10 dB/GHz(calculated from 3.395 GHz with-2.873 dB to 3.507 GHz with-28.42 dB).This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz.Having been presented in this article,the measurement results agree well with the simulation results,which validates our idea.
文摘This paper reports the use of the fast Fourier transform (FFT) in the direct Fourier transform method (DFM) in Computerized Tomography (CT) reconstruction. Phase corrections are needed in the CT reconstruction. In order to eliminate the image distortion from the basic DFM, Padding and band-pass filters are used in the improved DFM. Finally, some reconstructions from simulated projections and several experimental results are given.
基金Project supported by the National Natural Science Foundation of China(Grant No.61371009)the Fund from the Chinese Ministry of Science and Technology(Grant No.2014AA032703)
文摘This study presents two multimode stepped-impedance structures to design single-and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth (FBW) of 25.6%. Four stubs (two low frequency and two high frequency ones) are connected to the rectangular patch in the center to construct a quadruple-mode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single-and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.
文摘We have designed and proposed the edge modes supported by graphene ribbons and the planar band-pass filter consist- ing of graphene ribbons coupled to a graphene ring resonator by using the finite-difference time-domain numerical method. Simulation results show that the edge modes improve the electromagnetic coupling between devices. This structure works as a novel, tunable mid-infrared band-pass filter. Our studies will benefit the fabrication of planar, ultra-compact nano-scale devices in the mid-infrared region. A power splitter consisting of two output ribbons that is useful in photonic integrated devices and circuits is also designed and simulated. These devices are useful for designing ultra-compact planar devices in photonic integrated circuits.
文摘An Electromagnetic Band Gap (EBG) loaded square waveguide Band-Pass Filter (BPF) is proposed in this paper. It’s simply composed by symmetrically loading periodical metal diaphragms on each wall of a square waveguide. The influences of insert sizes and loading periods on the overall BPF performances are analyzed. Experimental results agree well with those predicted. 6 GHz pass-band with insert loss less than 1 dB, 2.5 GHz stop-band and larger than 25 dB polarization isolation can be obtained. The BPF can be applied in dual-polarized waveguide-based antenna-feed systems.
文摘A terahertz(THz) waveguide band-pass filter using an iris inductive window coupled structure was designed and fabricated.The filter was designed at0.22 THz with a pass band of 20 GHz.The measured results show that the center frequency is 0.218 THz with a pass band of 0.205 THz to 0.231 THz,the minimum insertion loss is 1.26 d B at 0.224 THz,and the return loss is less than 13.1 d B.The stop-band suppression is65.6 d B at 0.193 THz and 51.8 d B at 0.243 THz,respectively,which means a good performance of high stop-band suppression.A good agreement exists between the measured S-parameters and the simulated ones,especially in the upper band.The proposed THz waveguide filter has potential applications in THz communications.
文摘The multilayer structure is a promising technique used to minimize the size of planar microstrip filters.In the flexible design and incorporation of other microwave components,multilayer band-pass filter results in better and enhanced dimensions.This paper introduces a microstrip fifth-generation(5G)low-frequency band of 2.52–2.65 GHz using a parallel-coupled line(PCL)Bandpass filter and multilayer(ML)hairpin Bandpass filter.The targeted four-pole resonator has a center frequency of 2.585 GHz with a bandwidth of 130 MHz.The filters are designed with a 0.1 dB passband ripple with a Chebyshev response.The hairpin-line offers compact filter design structures.Theoretically,they can be obtained by bending half-wavelength resonator resonators with parallel couplings into a“U”shape.The proposed configuration of the parllel-coupled line resonator is used to design the ML band-pass filter.The FR4 substrate with a dielectric constant(Er)of 4.3 and 1.6 mm thickness was used.A comparative analysis between the simulated insertion loss and the reflection cofficient of substrates RO3003 and FR4 was performed to validate the eficiency of the proposed filter design.Simulation of PCL filter is accom-plished using computer simulation technology(CST)and an advanced design system(ADS)software.The PCL Bandpass filter was experimentally validated and a total tally between simulation results and measured results were achieved demonstrating a well-measured reflection coefficient.The simulated results obtained by the hairpin ML bandpass filter show that the circuit performs well in terms of Scattering(S)parameters and the filter size is significantly reduced.
文摘This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resonator (SIR), however, it does not give analytical equations or prediction for the dual-resonance characteristics of the NPHR structure discussed in this paper. Consequently, a circuit model is proposed to analyze the dual-resonance characteristics of NPHRs. Analytical equations are derived, showing that the frequency ratio of a dual-band NPHR can be determined by the ratio of turns. EM simulation and experimental results have shown good agreement with the circuit analysis. The derived analytical equations from circuit model can be used for fast design of NPHRs. A step-width aperture is proposed to independently control the coupling coefficients at the each band of NPHRs. A third order dual-passband filter has been designed and fabricated. The filter has 3.3% and 3% fractional bandwidths at 789 MHz and 2402 MHz, respectively. The designed prototype filter shows that NPHRs can be utilized to realize compact filters with dual-band characteristics. The filter design can be extended from engineering perspective for application in wireless communication systems.
文摘在传统微带线结构基础上利用阶跃阻抗并联短截线SISS(Step-Impedance Shunt Stubs)的带阻及慢波抑制特性,提出了一种新的基于SISS缺陷微带线结构S-DMS(SISS Defected Microstrip Structure),利用该结构设计制作了具有谐波抑制功能的双通带滤波器。采用HFSS进行仿真优化,在此基础上进行了实物加工,获得了通带中心频率为3.5 GHz,8.5 GHz,插入损耗分别为0.45 d B,2.7 d B,3 d B带宽分别是550 MHz,260 MHz,带外最大抑制小于-40 d B的实测结果,与仿真结果相当吻合。结果表明该双通带滤波器具有良好的谐波抑制能力、小带内衰减和宽且深的阻带特性。