A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 GHz.The antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiatio...A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 GHz.The antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiation part of the antenna array.High gain,wideband,and high radiation efficiency characteristics can be achieved by adopting a low insertion loss feeding network and broadband antenna elements.For the linearly polarized antenna array,simulation results show that the impedance bandwidth of the 2×2 antenna subarray reaches 21.6%,while the maximum gain achieves 15.1 dBi and has a fluctuation of less than 0.4 dBi within the working bandwidth.Simulation results of the 8×8 linearly polarized antenna array show a bandwidth of 21.6%and a gain of(26.1±1)dBi with an antenna efficiency of more than 80%.For the 8×8 circularly polarized antenna array,simulation results show that an impedance bandwidth of 18.2%and an axial ratio(AR)bandwidth of 13.3%are obtained.Gain and efficiency of up to 27.6 dBi and 80%are achieved,respectively.A prototype of antenna array is fabricated,and results are compared and analyzed.展开更多
We propose a switchable THz metamaterial that can be switched between two functions of half-wave plate and quarter-wave plate.The two switchable functions can be simply achieved by inserting a VO2 film in the metamate...We propose a switchable THz metamaterial that can be switched between two functions of half-wave plate and quarter-wave plate.The two switchable functions can be simply achieved by inserting a VO2 film in the metamaterial design.Finite-difference time-domain(FDTD)simulation results show that the proposed metamaterial can convert x-polarized incident wave to y-polarized reflected wave when VO2 is at metal phase,and convert x-polarized wave to circularly polarized wave when VO2 is at insulator phase.The metamaterial performs well in the two functions,i.e.,the same broad working frequency band and near perfect polarization conversion.The switching effect originates from the switchable Fabry-Perot cavity length induced by the phase change of VO2.We believe that our findings provide a reference in designing switchable metamaterials.展开更多
Antenna array is one of the methods which can generate Orbital Angular Momentum(OAM)waves.However,OAM waves generated by different antenna arrays have different characteristics of Electric-field(E-field)com-ponents...Antenna array is one of the methods which can generate Orbital Angular Momentum(OAM)waves.However,OAM waves generated by different antenna arrays have different characteristics of Electric-field(E-field)com-ponents'distribution and radiation patterns.In order to solve this problem,we derive E-feld formulas of OAM waves generated by different kinds of dipole antenna array in this paper.The dipole antenna arrays are arranged by three methods:1)antenna elements are in the same direction of y axis,2)antenna elements are in the radial direction and 3)antenna elements are in the azimuthal direction.Results show that x components,y components and z components carry different OAM modes under the three conditions.Simulation results show that the same direction antenna array produces the best OAM waves because the y component is dominated by OAM mode l and RHCP/LHCP waves are negligible in energy,while the pure OAM waves carried by the z components generated by the other two antenna arrays have little energy.In addition,only the radiation pattern ofl=0 produced by the same direction antenna array does not have a null zone in the propagation direction.Radiation patterns of l=±1 do not have null zones in the propagation direction generated by other two antenna arrays.展开更多
文摘A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 GHz.The antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiation part of the antenna array.High gain,wideband,and high radiation efficiency characteristics can be achieved by adopting a low insertion loss feeding network and broadband antenna elements.For the linearly polarized antenna array,simulation results show that the impedance bandwidth of the 2×2 antenna subarray reaches 21.6%,while the maximum gain achieves 15.1 dBi and has a fluctuation of less than 0.4 dBi within the working bandwidth.Simulation results of the 8×8 linearly polarized antenna array show a bandwidth of 21.6%and a gain of(26.1±1)dBi with an antenna efficiency of more than 80%.For the 8×8 circularly polarized antenna array,simulation results show that an impedance bandwidth of 18.2%and an axial ratio(AR)bandwidth of 13.3%are obtained.Gain and efficiency of up to 27.6 dBi and 80%are achieved,respectively.A prototype of antenna array is fabricated,and results are compared and analyzed.
基金Supported by the Scientific and Technological Developing Scheme of Jilin Province(Grant No.20180101281JC)"135"Research Project of Education Bureau of Jilin Province(Grant No.JJKH20190579KJ)"111"Project of China(Grant No.D17017)。
文摘We propose a switchable THz metamaterial that can be switched between two functions of half-wave plate and quarter-wave plate.The two switchable functions can be simply achieved by inserting a VO2 film in the metamaterial design.Finite-difference time-domain(FDTD)simulation results show that the proposed metamaterial can convert x-polarized incident wave to y-polarized reflected wave when VO2 is at metal phase,and convert x-polarized wave to circularly polarized wave when VO2 is at insulator phase.The metamaterial performs well in the two functions,i.e.,the same broad working frequency band and near perfect polarization conversion.The switching effect originates from the switchable Fabry-Perot cavity length induced by the phase change of VO2.We believe that our findings provide a reference in designing switchable metamaterials.
基金This study was supported by the National Natural Science Foundation of China(NSFC 61771213)Shanghai Aerospace Science and Technology Innovation Fund(SAST2017-113)the Fundamental Research Funds for the Central Universities(HUST2016JCTD203,2018KFYYXJJ140).
文摘Antenna array is one of the methods which can generate Orbital Angular Momentum(OAM)waves.However,OAM waves generated by different antenna arrays have different characteristics of Electric-field(E-field)com-ponents'distribution and radiation patterns.In order to solve this problem,we derive E-feld formulas of OAM waves generated by different kinds of dipole antenna array in this paper.The dipole antenna arrays are arranged by three methods:1)antenna elements are in the same direction of y axis,2)antenna elements are in the radial direction and 3)antenna elements are in the azimuthal direction.Results show that x components,y components and z components carry different OAM modes under the three conditions.Simulation results show that the same direction antenna array produces the best OAM waves because the y component is dominated by OAM mode l and RHCP/LHCP waves are negligible in energy,while the pure OAM waves carried by the z components generated by the other two antenna arrays have little energy.In addition,only the radiation pattern ofl=0 produced by the same direction antenna array does not have a null zone in the propagation direction.Radiation patterns of l=±1 do not have null zones in the propagation direction generated by other two antenna arrays.
