The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded...The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded dielectric resonator included in stripline elevated ferrite film circulator, the off diagonal components of the permeability tensor are taken as the perturbation. The electromagnetic fields computations are done for unperturbed structure. The dipolar resonant frequencies corresponding to harmonics of the resonant modes are then calculated using the perturbation integrals. The quality factor of the circulator is derived in terms of these dipolar resonant frequencies. Energy integrals are calculated to find the energy stored in the ferrite and dielectic layers. An analytical expression for the input conductance of the elevated ferrite film circulators is derived by using the quality factor and energy integrals. In this expression the ferrite and dielectric layers can have different permittivities. Some discussions about the effect of ferrite film thickness and permittivity mismatch on the bandwidth of the circulator are investigated by HFSS commercial software.展开更多
Strontium ferrites with different Bi2O3 content are prepared by the solid phase method, and their magnetic properties are investigated primarily. The Bi2O3 additive and sintering temperature separately exhibit a stron...Strontium ferrites with different Bi2O3 content are prepared by the solid phase method, and their magnetic properties are investigated primarily. The Bi2O3 additive and sintering temperature separately exhibit a strong effect on the sintering density, crystal structure, and magnetic properties of the ferrites. As to the ferrites with 3 wt% Bi2O3, the relatively high sintering density ρs, saturation magnetization Ms, and intrinsic coercivity HCi can be obtained at a low sintering temperature of 900℃ even much lower. Furthermore, the effective magnetic anisotropy constant Keff and magnetic anisotropy field Ha of the ferrites are calculated from the magnetization curve by the law of approach to saturation. It is suggested that the low-temperature sintered SrFe12O19 ferrites with Ms of 285.6 kA/m and Ha of 1564.6 kA/m possess a significant potentiality for applying in the self-biased low-temperature co-fired ceramics circulators from 34 to 40GHz.展开更多
A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The tran...A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.展开更多
A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW)structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circu...A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW)structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 pm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG)structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.展开更多
With the development of long range missile early warning radar,MMW phased array antenna is strongly needed. The phase shifter (PS) with high power capability and low insertion loss is a key technology in this kind of ...With the development of long range missile early warning radar,MMW phased array antenna is strongly needed. The phase shifter (PS) with high power capability and low insertion loss is a key technology in this kind of radar. Ferrite dielectric waveguide is introduced in this paper to manufacture PS,the cross section can be enlarged to 4 times of that of the conventional PS,which facilitates the engineering realization with reduced insertion loss. A novel vector base function of Galerkin method is proposed in calculating the eigenvalue of ferrite dielectric waveguide. The field distribution of main mode,power density and efficiency of 94 GHz difference phase shifter are also given.展开更多
Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveg...Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveguides and ferrite disks to support non-reciprocal mode coupling.The simulated performance of symmetrically designed circulator shows that it has an insertion loss of roughly 0.5 dB while the isolation and return loss is more than 12 dB in the frequency range of 6.0 GHz–10.0 GHz(relative bandwidth of 50%).Equivalent circuit model has been proposed to explain the operating mechanism of the plasmonic circulator.The equivalent circuit model,numerical simulations,and experimental results are consistent with each other,which demonstrates the good performance of the proposed plasmonic circulator.展开更多
In this work, a waveguide structure consisting of a new artificial negative index material (NIM) surrounded by a nonlinear cover and a ferrite (YIG) substrate has been designed and investigated. We apply the boundary ...In this work, a waveguide structure consisting of a new artificial negative index material (NIM) surrounded by a nonlinear cover and a ferrite (YIG) substrate has been designed and investigated. We apply the boundary conditions and impose the condition of negative effective permeability of the ferrite slab to derive the dispersion relation related to the proposed structure. The NIM permittivity and permeability are not constant and depend on the operating frequency. The dispersion properties of the nonlinear electromagnetic surface waves (NEM) are analyzed and the associated propagation index is calculated. Results show that the dispersion could be tuned and controlled by selecting the NIM film thickness and the film-cover interface nonlinearity. The proposed structure is supporting unusual types of NEM surface waves having a non-reciprocal behavior widely used in designing optoelectronic devices.展开更多
利用外观形貌分析、扫描电镜(scanning electron microscope,SEM)形貌分析、力学性能测试、化学成分分析及显微组织检测等方法,对断裂的循环水泵轴进行了系统失效分析。结果表明,该泵轴轴颈变截面加工不规范,根部存在车削凹槽,导致轴径...利用外观形貌分析、扫描电镜(scanning electron microscope,SEM)形貌分析、力学性能测试、化学成分分析及显微组织检测等方法,对断裂的循环水泵轴进行了系统失效分析。结果表明,该泵轴轴颈变截面加工不规范,根部存在车削凹槽,导致轴径变截面产生较大应力集中。泵轴加工阶段未进行调质处理,泵体金相组织为网状铁素体+珠光体,致使材料强度及韧性下降,对裂纹敏感性显著上升。在运行过程中,裂纹在轴颈变截面处的车削凹槽(应力集中区)萌生,以疲劳裂纹形式扩展,最终引发泵轴发生高周低应力疲劳断裂。建议优化轴颈变截面过渡结构,加强对循环水泵轴热加工与热处理的验收控制,选用组织与性能良好、力学性能合格的泵轴材料,并在运行过程中加强对因机组负荷频繁变化引发的轴体损伤检查,避免类似断裂失效故障再次发生。展开更多
文摘The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded dielectric resonator included in stripline elevated ferrite film circulator, the off diagonal components of the permeability tensor are taken as the perturbation. The electromagnetic fields computations are done for unperturbed structure. The dipolar resonant frequencies corresponding to harmonics of the resonant modes are then calculated using the perturbation integrals. The quality factor of the circulator is derived in terms of these dipolar resonant frequencies. Energy integrals are calculated to find the energy stored in the ferrite and dielectic layers. An analytical expression for the input conductance of the elevated ferrite film circulators is derived by using the quality factor and energy integrals. In this expression the ferrite and dielectric layers can have different permittivities. Some discussions about the effect of ferrite film thickness and permittivity mismatch on the bandwidth of the circulator are investigated by HFSS commercial software.
基金Supported by the Scientific Research Foundation of Education Office of Sichuan Province under Grant No 13Z198the Young and Middle-aged Academic Leaders of Scientific Research Funds of Chengdu University of Information Technology under Grant No J201222
文摘Strontium ferrites with different Bi2O3 content are prepared by the solid phase method, and their magnetic properties are investigated primarily. The Bi2O3 additive and sintering temperature separately exhibit a strong effect on the sintering density, crystal structure, and magnetic properties of the ferrites. As to the ferrites with 3 wt% Bi2O3, the relatively high sintering density ρs, saturation magnetization Ms, and intrinsic coercivity HCi can be obtained at a low sintering temperature of 900℃ even much lower. Furthermore, the effective magnetic anisotropy constant Keff and magnetic anisotropy field Ha of the ferrites are calculated from the magnetization curve by the law of approach to saturation. It is suggested that the low-temperature sintered SrFe12O19 ferrites with Ms of 285.6 kA/m and Ha of 1564.6 kA/m possess a significant potentiality for applying in the self-biased low-temperature co-fired ceramics circulators from 34 to 40GHz.
基金supported by the National Natural Science Foundation of China under Grant No.61171006
文摘A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated.The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method.The transmission characteristics of the circulator are simulated by the finite element method.We perform the experiments in the microwave regime to validate the numerical results.At the central frequency of 10.15 GHz,the measured isolation and insertion loss of the circulator reaches-30.2 and-3.93 d B,respectively.The bandwidth of the circulator is about 550 MHz.The optimal experimental value of isolation is higher than the numerical value.
基金supported by the National Basic Research Program of China under Grant No.61363Z06.1
文摘A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW)structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 pm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG)structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.
文摘With the development of long range missile early warning radar,MMW phased array antenna is strongly needed. The phase shifter (PS) with high power capability and low insertion loss is a key technology in this kind of radar. Ferrite dielectric waveguide is introduced in this paper to manufacture PS,the cross section can be enlarged to 4 times of that of the conventional PS,which facilitates the engineering realization with reduced insertion loss. A novel vector base function of Galerkin method is proposed in calculating the eigenvalue of ferrite dielectric waveguide. The field distribution of main mode,power density and efficiency of 94 GHz difference phase shifter are also given.
基金Project supported by the Six-Talent-Peaks Project in Jiangsu Province of China(Grant No.XYDXX-072)the National Natural Science Foundation of China(Grant No.61372048).
文摘Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveguides and ferrite disks to support non-reciprocal mode coupling.The simulated performance of symmetrically designed circulator shows that it has an insertion loss of roughly 0.5 dB while the isolation and return loss is more than 12 dB in the frequency range of 6.0 GHz–10.0 GHz(relative bandwidth of 50%).Equivalent circuit model has been proposed to explain the operating mechanism of the plasmonic circulator.The equivalent circuit model,numerical simulations,and experimental results are consistent with each other,which demonstrates the good performance of the proposed plasmonic circulator.
文摘In this work, a waveguide structure consisting of a new artificial negative index material (NIM) surrounded by a nonlinear cover and a ferrite (YIG) substrate has been designed and investigated. We apply the boundary conditions and impose the condition of negative effective permeability of the ferrite slab to derive the dispersion relation related to the proposed structure. The NIM permittivity and permeability are not constant and depend on the operating frequency. The dispersion properties of the nonlinear electromagnetic surface waves (NEM) are analyzed and the associated propagation index is calculated. Results show that the dispersion could be tuned and controlled by selecting the NIM film thickness and the film-cover interface nonlinearity. The proposed structure is supporting unusual types of NEM surface waves having a non-reciprocal behavior widely used in designing optoelectronic devices.
文摘利用外观形貌分析、扫描电镜(scanning electron microscope,SEM)形貌分析、力学性能测试、化学成分分析及显微组织检测等方法,对断裂的循环水泵轴进行了系统失效分析。结果表明,该泵轴轴颈变截面加工不规范,根部存在车削凹槽,导致轴径变截面产生较大应力集中。泵轴加工阶段未进行调质处理,泵体金相组织为网状铁素体+珠光体,致使材料强度及韧性下降,对裂纹敏感性显著上升。在运行过程中,裂纹在轴颈变截面处的车削凹槽(应力集中区)萌生,以疲劳裂纹形式扩展,最终引发泵轴发生高周低应力疲劳断裂。建议优化轴颈变截面过渡结构,加强对循环水泵轴热加工与热处理的验收控制,选用组织与性能良好、力学性能合格的泵轴材料,并在运行过程中加强对因机组负荷频繁变化引发的轴体损伤检查,避免类似断裂失效故障再次发生。
基金Supported by the Fundamental Research Funds for the Central Universities(ZYGX2010J039)the Defense Pre-Research Foundation of China(9140A12020311DZ0202)the Program for NCET(NCET-12-0099)
