A gradient metamaterial with varying-stiffness local resonators is proposed to open the multiple bandgaps and further form a broad fusion bandgap.First,three local resonators with linearly increasing stiffness are per...A gradient metamaterial with varying-stiffness local resonators is proposed to open the multiple bandgaps and further form a broad fusion bandgap.First,three local resonators with linearly increasing stiffness are periodically attached to the spring-mass chain to construct the gradient metamaterial.The dispersion relation is then derived based on Bloch's theorem to reveal the fusion bandgap theoretically.The dynamic characteristic of the finite spring-mass chain is investigated to validate the fusion of multiple bandgaps.Finally,the effects of the design parameters on multiple bandgaps are discussed.The results show that the metamaterial with a non-uniform stiffness gradient pattern is capable of opening a broad fusion bandgap and effectively attenuating the longitudinal waves within a broad frequency region.展开更多
提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求...提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S.利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S21参数则更方便评价噪声隔离度.根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法.采用3D全波电磁仿真验证了1D有限元算法的合理性.展开更多
This work demonstrates the design of a single band Electromagnetic Band Gap(EBG)antenna by employing an open stub EBG microstrip of a patch antenna for better achievements in terms of its performance to be utilized in...This work demonstrates the design of a single band Electromagnetic Band Gap(EBG)antenna by employing an open stub EBG microstrip of a patch antenna for better achievements in terms of its performance to be utilized in a reconfigurable harvester to operate over a wide input power range.The EBG antenna has been used to gather RF energy and a FET-transistor has been obtain-able to determine and control the powerflow with the intention to operate at the same time for a different level of input power.The measured data of the EBG antenna shows a directivity of 8.52 dBi,a gain of 7.18 dBi,a return loss of-27 dB with a radiation efficiency of 84.3%,showing a clear enhancement in directivity,peak realized gain,and radiation efficiency by 41.76%,25.61%,and 17.12%respectively compared with a regular reference antenna;without utilized the EBG structure.Moreover,the harvester design accomplishes 40%of RF-DC power conversion efficiency over a wide dynamic input power range from-15 to 27 dBm,and its peak is around 78%.The harvester is designed to work at the ISM band for 915 MHz and is suitable for Wireless Power Transfer(WPT)uses.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12122206,52175125,12272129,12304309,and 12302039)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24A020006)+1 种基金the Hong Kong Scholars Program of China(No.XJ2022012)the Natural Science Foundation of Hunan Province of China(No.2024JJ4004)。
文摘A gradient metamaterial with varying-stiffness local resonators is proposed to open the multiple bandgaps and further form a broad fusion bandgap.First,three local resonators with linearly increasing stiffness are periodically attached to the spring-mass chain to construct the gradient metamaterial.The dispersion relation is then derived based on Bloch's theorem to reveal the fusion bandgap theoretically.The dynamic characteristic of the finite spring-mass chain is investigated to validate the fusion of multiple bandgaps.Finally,the effects of the design parameters on multiple bandgaps are discussed.The results show that the metamaterial with a non-uniform stiffness gradient pattern is capable of opening a broad fusion bandgap and effectively attenuating the longitudinal waves within a broad frequency region.
文摘提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S.利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S21参数则更方便评价噪声隔离度.根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法.采用3D全波电磁仿真验证了1D有限元算法的合理性.
基金The authors gratefully acknowledge Qassim University,represented by the Deanship of Scientific Research,on the financial support for this research under the number(10262-qec-2020-1-3-I)the academic year 1441 AH/2020 AD.
文摘This work demonstrates the design of a single band Electromagnetic Band Gap(EBG)antenna by employing an open stub EBG microstrip of a patch antenna for better achievements in terms of its performance to be utilized in a reconfigurable harvester to operate over a wide input power range.The EBG antenna has been used to gather RF energy and a FET-transistor has been obtain-able to determine and control the powerflow with the intention to operate at the same time for a different level of input power.The measured data of the EBG antenna shows a directivity of 8.52 dBi,a gain of 7.18 dBi,a return loss of-27 dB with a radiation efficiency of 84.3%,showing a clear enhancement in directivity,peak realized gain,and radiation efficiency by 41.76%,25.61%,and 17.12%respectively compared with a regular reference antenna;without utilized the EBG structure.Moreover,the harvester design accomplishes 40%of RF-DC power conversion efficiency over a wide dynamic input power range from-15 to 27 dBm,and its peak is around 78%.The harvester is designed to work at the ISM band for 915 MHz and is suitable for Wireless Power Transfer(WPT)uses.
