In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance fre...In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.展开更多
A novel microwave cloak using circular split ring resonator(SRR)based metamaterial structure has been proposed in this paper.The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sh...A novel microwave cloak using circular split ring resonator(SRR)based metamaterial structure has been proposed in this paper.The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sheets printed with circular split ring resonators of spatially varying and anisotropic material properties.The article also focuses on the phenomenon of resonant splitting in circular SRR microwave cloak.A detailed analysis of various linear metamaterial arrays and their response has also been elucidated.展开更多
The transmission properties of double-ring split ring resonator(SRR) arrays and closed ring resonator arrays are measured using terahertz(THz) time-domain spectroscopy. This technique allows for the simultaneous measu...The transmission properties of double-ring split ring resonator(SRR) arrays and closed ring resonator arrays are measured using terahertz(THz) time-domain spectroscopy. This technique allows for the simultaneous measurement of the amplitude and phase of the transmission coefficient as a function of frequency. The ability to directly measure the phase spectrum is expected to be important in characterizing potential negative index media. In the employed experimental geometry, THz pulses are normally incident on the arrays. Thus, the magnetic field lies in the plane of the arrays and cannot contribute to the magnetic resonance of the SRR. However, it is found that the electric field, when appropriately polarized, can couple to the magnetic resonance. Shifts in the resonance properties with changes in the SRR dimensions and the substrate medium are measured, the results of which are consistent with theory.展开更多
This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode（1500 nm）is far from the pump mode（980 nm）, which can depress the detection noise from the pump light. The...This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode（1500 nm）is far from the pump mode（980 nm）, which can depress the detection noise from the pump light. The laser intensities of the two modes simultaneously increase by more than 10^3 in amplitude, which can intensify the absorption efficiency of the pumping light and enhance the plasmonic lasing. The plasmonic lasing is a sensitive sensor. When a single protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap of the split ring, the lasing spectrum moves by 0.031 nm, which is much larger than the detection limit of 10^-5 nm. Moreover, the lasing intensity is also very sensitive to the trapped nanoparticle. It reduces to less than 1/600 when a protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap.展开更多
In this paper, we present the complex permittivity measurement of low-loss substrates based on a microstrip-line-excited split-ring resonator (SRR). Permittivity of an unknown substrate is calculated based on the chan...In this paper, we present the complex permittivity measurement of low-loss substrates based on a microstrip-line-excited split-ring resonator (SRR). Permittivity of an unknown substrate is calculated based on the change in oscillation frequency of SRR caused by the material-under-test (MUT) above the SRR. Theoretical analysis and results of the simulations and experiments demonstrate the microstrip-line-excited SRR can be used to effectively improve measurement sensitivity. Simple equations for measurement of low-loss substrates using SRR are proposed and experimentally verified.展开更多
Moisture ingression accelerates the ageing and degradation of the oil-paper insulation.Rapid and accurate moisture assessment of power apparatus in the field is thus essential.In this paper,an innovative design of a m...Moisture ingression accelerates the ageing and degradation of the oil-paper insulation.Rapid and accurate moisture assessment of power apparatus in the field is thus essential.In this paper,an innovative design of a microstrip petal-like complementary split ring resonator(MPCSRR)is proposed for the moisture assessment of the oil-paper insulation in the GHz range.The MPCSRR has advantages in concentrating the electromagnetic field,significantly increasing the number of resonance peaks,and achieving a sensitivity of approximately 3-4 times higher than the traditional microstrip ring resonators(MRRs).A mathematical model for analysing the dielectric response is established,combining the theoretical analysis and equivalent circuit model.The effects of microstrip width and substrate thickness on impedance matching,as well as the incidence depth and test sensitivity of the resonator,are explored using simulation.The experimental results demonstrate that the MPCSRR achieves rapid moisture detection within tens of seconds and accurately characterises the wetness of the oil-paper insulation.A moisture assess-ment model based on Lasso regression achieves an accuracy of 4%,confirming the reliability and validity of the proposed method.The results also verify that the sensitivity of the MPCSRR is also higher than that of the traditional MRR,showing its potential for precise and efficient moisture detection in oil-paper insulation.展开更多
An ultrasensitive metamaterial sensor based on double-slot vertical split ring resonators(DVSRRs) is designed and numerically calculated in the terahertz frequency. This DVSRR design produces a fundament LC resonance ...An ultrasensitive metamaterial sensor based on double-slot vertical split ring resonators(DVSRRs) is designed and numerically calculated in the terahertz frequency. This DVSRR design produces a fundament LC resonance with a quality factor of about 20 when the incidence magnetic field component normal to the DVSRR array. The resonant characteristics and sensing performance of the DVSRR array design are systematically analyzed employing a contrast method among three similar vertical split ring resonator(SRRs) structures. The research results show that the elimination of bianisotropy, induced by the structural symmetry of the DVSRR design, helps to achieve LC resonance of a high quality factor. Lifting the SRRs up from the substrate sharply reduces the dielectric loss introduced by the substrate. All these factors jointly result in superior sensitivity of the DVSRR to the attributes of analytes. The maximum refractive index sensitivity is 788 GHz/RIU or 1.04 × 10~5 nm∕RIU.Also, the DVSRR sensor maintains its superior sensing performance for fabrication tolerance ranging from -4% to 4% and wide range incidence angles up to 50° under both TE and TM illuminations.展开更多
A novel single-cavity equilateral triangular substrate integrated waveguide(TSIW) bandpass filter(BPF) with a complementary triangular split ring resonator(CTSRR) is designed in this paper. A metallic via-hole is used...A novel single-cavity equilateral triangular substrate integrated waveguide(TSIW) bandpass filter(BPF) with a complementary triangular split ring resonator(CTSRR) is designed in this paper. A metallic via-hole is used to split the degenerate modes and adjust the transmission zeros(TZs) properly. Meanwhile, the CTSRR is utilized as a resonator to work together with the degenerate modes of the TSIW cavity. The resonant frequency of the CTSRR can be adjusted by its own size. Meanwhile, a TZ is observed in the lower band due to the CTSRR. Finally, a 16% 3 dB fractional bandwidth(FBW) triple-mode TSIW BPF with three TZs in both lower and upper bands is simulated, fabricated, and measured. There is a good agreement between the simulated and measured ones.展开更多
Microwaves,which have a∼10-cm wavelength,can penetrate deeper into tissue than photons,heralding exciting deep tissue applications such as modulation or imaging via the thermoacoustic effect.Thermoacoustic conversion...Microwaves,which have a∼10-cm wavelength,can penetrate deeper into tissue than photons,heralding exciting deep tissue applications such as modulation or imaging via the thermoacoustic effect.Thermoacoustic conversion efficiency is however very low,even with an exogenous contrast agent.We break this low-conversion limit,using a split ring resonator to effectively collect and confine the microwaves into a submillimeter hot spot for ultrasound emission and achieve a conversion efficiency over 2000 times higher than other reported thermoacoustic contrast agents.Importantly,the frequency of emitted ultrasound can be precisely tuned and multiplexed by modulation of the microwave pulses.Such performance is inaccessible by a piezoelectric-based transducer or a photoacoustic emitter and,therefore,split ring resonators open up new opportunities to study the frequency response of cells in ultrasonic biomodulation.For applications in deep tissue localization,a split ring resonator can be used as a wireless,battery-free ultrasound beacon placed under a breast phantom.展开更多
Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cyl...Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cylindrical shaped hyperlens can be used for super-resolution microwave focusing in a TE mode. Based on split ring resonators, the hyperlens satisfies a hyperbolic dispersion relationship. Simulations demonstrate that the focused spot size and position are insensitive to the rotation angle of the hyperlens around its geometric center. Experimental results show that a focused spot size 1/3 of the vacuum wavelength is achieved in the microwave band.展开更多
The residual stresses in the wall of a SUS304 stainless steel cylindrical drawing cup were evaluated by split-ring tests, and the influences of stamping die parame- ters on the residual stress were investigated. A new...The residual stresses in the wall of a SUS304 stainless steel cylindrical drawing cup were evaluated by split-ring tests, and the influences of stamping die parame- ters on the residual stress were investigated. A new theoretical model of a split-ring test was developed to evaluate the resid- ual stress in a ring, which was verified to be reasonable and reliable by numerical simulations with ABAQUS code and by nanoindentation tests. Seven groups of split-ring tests were completed, and the residual stresses were calculated according to the theoretical model. The split-ring test results showed that the circumferential residual stress in the wall of the SUS304 stainless steel cylindrical drawing cup was very large and did not change with the different die comer radius. The circumferential residual stress first increased with the increase of drawing punch-die clearance, then was almost unchanged when the clearance increased greater than blank thickness 1 mm. Thus, a smaller clearance was suggested to be chosen to reduce the residual stress in the wall of the SUS304 stainless steel drawing cup.展开更多
Effects of oblique incidence of terahertz waves on the response of planar split-ring resonators are investigated, both experimentally and by simulation. It is found that the incident angle dependent phase delay and co...Effects of oblique incidence of terahertz waves on the response of planar split-ring resonators are investigated, both experimentally and by simulation. It is found that the incident angle dependent phase delay and coupling conditions of neighboring split-ring resonator （SRR） units play important roles and greatly change both the transmission and reflection spectra for the resonant feature of linear charge oscillations. Our results show that the SRR structure-supported magne- toelectric couplings at oblique excitation are trivial and can be ignored. A highly symmetric response is found in the cross-polarization effects, which may manifest the bianisotropic properties of the SRR system but this needs further study.展开更多
Novel band-stop filters with circular split-ring resonators based on the metal-insulator-metal （MIM） structure are presented, with their transmission properties of SPPs propagating through the filter simulated by th...Novel band-stop filters with circular split-ring resonators based on the metal-insulator-metal （MIM） structure are presented, with their transmission properties of SPPs propagating through the filter simulated by the finite-difference time-domain （FDTD） method, The variation of the gap of the split ring can affect the transmission characteristics, i.e., the transmission spectrum of SPPs exhibiting a shift, which is useful for modulating the filter. Linear and nonlinear media are used in the resonator respectively. By varying the refractive index of the linear medium, the transmission properties can be changed obviously, and the effect caused by changing the incident intensity with a nonlinear medium is similar. Several resonant modes that are applicable can be enhanced by changing the position of the gap of the split ring. Thus, the transmission properties can be modulated by adjusting the size of the gap, varying the refractive index, and changing the incident intensity of the input light. These methods may play significant roles in applications of optical integrated circuits and nanostructural devices.展开更多
To use the single split-ring resonator （SRR） as a basic unit cell for small antenna with multi-band frequency response is proposed. The structure of antenna is consisted of a single spilt-ring resonator and a couple...To use the single split-ring resonator （SRR） as a basic unit cell for small antenna with multi-band frequency response is proposed. The structure of antenna is consisted of a single spilt-ring resonator and a coupled microstrip line. The designed antenna is numerically optimized with CST Microwave Studio. The radiation properties of the antenna show that there are three frequency bands among which two bands are 1.3 GHz and 2.1 GHz ultra-widehand （UWB）, respectively, where Sll is less than - 10 dB. The gain at every frequency for the multi-hand antenna is above 2.6 dBi, and it increases monotonously with the frequency in the two UWB.展开更多
An effective approach to expand the bandwidth of negative permeability of small-sized planax materials is proposed. Based on qualitative analysis of equivalent circuit models, the fractional bandwidth of an μ-negati...An effective approach to expand the bandwidth of negative permeability of small-sized planax materials is proposed. Based on qualitative analysis of equivalent circuit models, the fractional bandwidth of an μ-negative （MNG） material is expanded from 3.53% up to 12.87% by adding split-ring resonators （SRRs） and arranging them by proposed steps. Moreover, the experimental results validate the effectiveness of bandwidth-expanding methods, which is promising for the extensive application of metamaterials in the microwave field.展开更多
基金supported by the Excellent Youth Foundation of Henan Provincial Scientific Committee,China(Grant No.0612002200)the Key Scientific and Technological Research Foundation of Henan Province,China(Grant No.0623021600)
文摘In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.
文摘A novel microwave cloak using circular split ring resonator(SRR)based metamaterial structure has been proposed in this paper.The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sheets printed with circular split ring resonators of spatially varying and anisotropic material properties.The article also focuses on the phenomenon of resonant splitting in circular SRR microwave cloak.A detailed analysis of various linear metamaterial arrays and their response has also been elucidated.
文摘The transmission properties of double-ring split ring resonator(SRR) arrays and closed ring resonator arrays are measured using terahertz(THz) time-domain spectroscopy. This technique allows for the simultaneous measurement of the amplitude and phase of the transmission coefficient as a function of frequency. The ability to directly measure the phase spectrum is expected to be important in characterizing potential negative index media. In the employed experimental geometry, THz pulses are normally incident on the arrays. Thus, the magnetic field lies in the plane of the arrays and cannot contribute to the magnetic resonance of the SRR. However, it is found that the electric field, when appropriately polarized, can couple to the magnetic resonance. Shifts in the resonance properties with changes in the SRR dimensions and the substrate medium are measured, the results of which are consistent with theory.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474097,11374099,and 11274116)the Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)China
文摘This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode（1500 nm）is far from the pump mode（980 nm）, which can depress the detection noise from the pump light. The laser intensities of the two modes simultaneously increase by more than 10^3 in amplitude, which can intensify the absorption efficiency of the pumping light and enhance the plasmonic lasing. The plasmonic lasing is a sensitive sensor. When a single protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap of the split ring, the lasing spectrum moves by 0.031 nm, which is much larger than the detection limit of 10^-5 nm. Moreover, the lasing intensity is also very sensitive to the trapped nanoparticle. It reduces to less than 1/600 when a protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap.
文摘In this paper, we present the complex permittivity measurement of low-loss substrates based on a microstrip-line-excited split-ring resonator (SRR). Permittivity of an unknown substrate is calculated based on the change in oscillation frequency of SRR caused by the material-under-test (MUT) above the SRR. Theoretical analysis and results of the simulations and experiments demonstrate the microstrip-line-excited SRR can be used to effectively improve measurement sensitivity. Simple equations for measurement of low-loss substrates using SRR are proposed and experimentally verified.
基金Ningbo Power Supply Company Science and Technology Program,Grant/Award Number:KJKY20230393。
文摘Moisture ingression accelerates the ageing and degradation of the oil-paper insulation.Rapid and accurate moisture assessment of power apparatus in the field is thus essential.In this paper,an innovative design of a microstrip petal-like complementary split ring resonator(MPCSRR)is proposed for the moisture assessment of the oil-paper insulation in the GHz range.The MPCSRR has advantages in concentrating the electromagnetic field,significantly increasing the number of resonance peaks,and achieving a sensitivity of approximately 3-4 times higher than the traditional microstrip ring resonators(MRRs).A mathematical model for analysing the dielectric response is established,combining the theoretical analysis and equivalent circuit model.The effects of microstrip width and substrate thickness on impedance matching,as well as the incidence depth and test sensitivity of the resonator,are explored using simulation.The experimental results demonstrate that the MPCSRR achieves rapid moisture detection within tens of seconds and accurately characterises the wetness of the oil-paper insulation.A moisture assess-ment model based on Lasso regression achieves an accuracy of 4%,confirming the reliability and validity of the proposed method.The results also verify that the sensitivity of the MPCSRR is also higher than that of the traditional MRR,showing its potential for precise and efficient moisture detection in oil-paper insulation.
基金National Natural Science Foundation of China(NSFC)(61327006,61620106014)
文摘An ultrasensitive metamaterial sensor based on double-slot vertical split ring resonators(DVSRRs) is designed and numerically calculated in the terahertz frequency. This DVSRR design produces a fundament LC resonance with a quality factor of about 20 when the incidence magnetic field component normal to the DVSRR array. The resonant characteristics and sensing performance of the DVSRR array design are systematically analyzed employing a contrast method among three similar vertical split ring resonator(SRRs) structures. The research results show that the elimination of bianisotropy, induced by the structural symmetry of the DVSRR design, helps to achieve LC resonance of a high quality factor. Lifting the SRRs up from the substrate sharply reduces the dielectric loss introduced by the substrate. All these factors jointly result in superior sensitivity of the DVSRR to the attributes of analytes. The maximum refractive index sensitivity is 788 GHz/RIU or 1.04 × 10~5 nm∕RIU.Also, the DVSRR sensor maintains its superior sensing performance for fabrication tolerance ranging from -4% to 4% and wide range incidence angles up to 50° under both TE and TM illuminations.
基金supported by the Six Talent Peaks Project in Jiangsu Province (KTHY-032)the Innovation and Entrepreneurship Training Program for College Students (SZDG2018024)+2 种基金the Natural Science Foundation of the Education Committee of Jiangsu Province, China (18KJA510003)the Open Project of the National Laboratory of Solid State Microstructure (M30050)the Sponsored Foundation of Nanjing University of Posts and Telecommunications (NY217085,NY218074)
文摘A novel single-cavity equilateral triangular substrate integrated waveguide(TSIW) bandpass filter(BPF) with a complementary triangular split ring resonator(CTSRR) is designed in this paper. A metallic via-hole is used to split the degenerate modes and adjust the transmission zeros(TZs) properly. Meanwhile, the CTSRR is utilized as a resonator to work together with the degenerate modes of the TSIW cavity. The resonant frequency of the CTSRR can be adjusted by its own size. Meanwhile, a TZ is observed in the lower band due to the CTSRR. Finally, a 16% 3 dB fractional bandwidth(FBW) triple-mode TSIW BPF with three TZs in both lower and upper bands is simulated, fabricated, and measured. There is a good agreement between the simulated and measured ones.
基金The project was supported by an Ignition Award from Boston University to J.X.C.
文摘Microwaves,which have a∼10-cm wavelength,can penetrate deeper into tissue than photons,heralding exciting deep tissue applications such as modulation or imaging via the thermoacoustic effect.Thermoacoustic conversion efficiency is however very low,even with an exogenous contrast agent.We break this low-conversion limit,using a split ring resonator to effectively collect and confine the microwaves into a submillimeter hot spot for ultrasound emission and achieve a conversion efficiency over 2000 times higher than other reported thermoacoustic contrast agents.Importantly,the frequency of emitted ultrasound can be precisely tuned and multiplexed by modulation of the microwave pulses.Such performance is inaccessible by a piezoelectric-based transducer or a photoacoustic emitter and,therefore,split ring resonators open up new opportunities to study the frequency response of cells in ultrasonic biomodulation.For applications in deep tissue localization,a split ring resonator can be used as a wireless,battery-free ultrasound beacon placed under a breast phantom.
基金the National Natural Science Foundation of China under Grants Nos.11374235,61271150,61007024,and 10904118
文摘Hyperlenses based on metamaterials can be applied to subwavelength imaging in the lightwave band. In this letter, we demonstrate both through simulations and experimentally verified results that our proposed half- cylindrical shaped hyperlens can be used for super-resolution microwave focusing in a TE mode. Based on split ring resonators, the hyperlens satisfies a hyperbolic dispersion relationship. Simulations demonstrate that the focused spot size and position are insensitive to the rotation angle of the hyperlens around its geometric center. Experimental results show that a focused spot size 1/3 of the vacuum wavelength is achieved in the microwave band.
基金supported in part by Xiangtan University Doctoral Fund, China (Grant 12QDZ17)the Excellent Youth Program of Education Bureau of Hunan Province, China (Grant 12B124)the Key Program of Hunan Provincial Natural Science Foundation United with Xiangtan, China (Grant 13JJ8005)
文摘The residual stresses in the wall of a SUS304 stainless steel cylindrical drawing cup were evaluated by split-ring tests, and the influences of stamping die parame- ters on the residual stress were investigated. A new theoretical model of a split-ring test was developed to evaluate the resid- ual stress in a ring, which was verified to be reasonable and reliable by numerical simulations with ABAQUS code and by nanoindentation tests. Seven groups of split-ring tests were completed, and the residual stresses were calculated according to the theoretical model. The split-ring test results showed that the circumferential residual stress in the wall of the SUS304 stainless steel cylindrical drawing cup was very large and did not change with the different die comer radius. The circumferential residual stress first increased with the increase of drawing punch-die clearance, then was almost unchanged when the clearance increased greater than blank thickness 1 mm. Thus, a smaller clearance was suggested to be chosen to reduce the residual stress in the wall of the SUS304 stainless steel drawing cup.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339800)the National Natural Science Foundation of China(Grant Nos.11374358 and 61077082)
文摘Effects of oblique incidence of terahertz waves on the response of planar split-ring resonators are investigated, both experimentally and by simulation. It is found that the incident angle dependent phase delay and coupling conditions of neighboring split-ring resonator （SRR） units play important roles and greatly change both the transmission and reflection spectra for the resonant feature of linear charge oscillations. Our results show that the SRR structure-supported magne- toelectric couplings at oblique excitation are trivial and can be ignored. A highly symmetric response is found in the cross-polarization effects, which may manifest the bianisotropic properties of the SRR system but this needs further study.
基金supported by the National Natural Science Foundation of China(Grant No.61001018)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2011FM009 and ZR2012FM011)+3 种基金the Research Fund of Shandong University of Science and Technology(SDUST),China(Grant No.2010KYJQ103)the SDUST Research Fund,China(Grant No.2012KYTD103)the Shandong Province Higher Educational Science and Technology Program,China(Grant No.J11LG20)the Qingdao Economic&Technical Development Zone Science&Technology Project,China(Grant No.2013-1-64)
文摘Novel band-stop filters with circular split-ring resonators based on the metal-insulator-metal （MIM） structure are presented, with their transmission properties of SPPs propagating through the filter simulated by the finite-difference time-domain （FDTD） method, The variation of the gap of the split ring can affect the transmission characteristics, i.e., the transmission spectrum of SPPs exhibiting a shift, which is useful for modulating the filter. Linear and nonlinear media are used in the resonator respectively. By varying the refractive index of the linear medium, the transmission properties can be changed obviously, and the effect caused by changing the incident intensity with a nonlinear medium is similar. Several resonant modes that are applicable can be enhanced by changing the position of the gap of the split ring. Thus, the transmission properties can be modulated by adjusting the size of the gap, varying the refractive index, and changing the incident intensity of the input light. These methods may play significant roles in applications of optical integrated circuits and nanostructural devices.
基金Sponsored by the BIT Developing Foundation(1070050320726)
文摘To use the single split-ring resonator （SRR） as a basic unit cell for small antenna with multi-band frequency response is proposed. The structure of antenna is consisted of a single spilt-ring resonator and a coupled microstrip line. The designed antenna is numerically optimized with CST Microwave Studio. The radiation properties of the antenna show that there are three frequency bands among which two bands are 1.3 GHz and 2.1 GHz ultra-widehand （UWB）, respectively, where Sll is less than - 10 dB. The gain at every frequency for the multi-hand antenna is above 2.6 dBi, and it increases monotonously with the frequency in the two UWB.
基金Project supported partially by the National Natural Science Foundation of China (Grant Nos. 60872034 and 60971029)the New-Century Talent Program of the Education Department of China (Grant No. NCET070154)+1 种基金the National Defense Research Funding (Grant No. ZJ10DZ02111)the Hi-Tech Research and Development Program of China (Grant No. 2009AA01Z231)
文摘An effective approach to expand the bandwidth of negative permeability of small-sized planax materials is proposed. Based on qualitative analysis of equivalent circuit models, the fractional bandwidth of an μ-negative （MNG） material is expanded from 3.53% up to 12.87% by adding split-ring resonators （SRRs） and arranging them by proposed steps. Moreover, the experimental results validate the effectiveness of bandwidth-expanding methods, which is promising for the extensive application of metamaterials in the microwave field.
