基于双三角形谐振环结构左手材料的矩形微带贴片天线

设计了一种双三角形谐振环结构的左手材料,通过理论计算和仿真实验证明了其具有电磁左手材料性质;将双三角形谐振环结构的左手材料加载在矩形贴片微带天线上,并给出了矩形微带贴片天线的结构参数;利用HFSS仿真软件对比了加载左手材料前后矩形贴片微带天线的性能,仿真结果表明,左手材料的加载提高了天线的带宽,增大了天线的增益,有效地抑制了旁瓣。     

新型一维微带开口环PBG结构的研究与设计

本文在对一维光子带隙PBG(Photonic Bandgap)结构进行设计时,提出一种新型的开口环PBG结构。该结构在接地板上刻蚀周期性的开口环,可分为圆形双开口环和方形双开口环两种结构。结果表明:圆形双开口环PBG结构简单易于实现,并且可以获得较宽的通带及较小的通带波纹。在圆型双开口环的基础上改进即得到方形双开口环PBG结构,结果显示出该方形结构具有良好的通带特性,并且可以有效地改善通带的平坦度,减小插损,适用于微波及毫米波集成电路。     

两种新型一维微带开口环PBG结构

本文在对一维光子带隙PBG(Photonic Bandgap)结构进行研究时,提出两种新型的开口环PBG结构,分别为圆形双开口环和方形双开口环两种结构。两种结构均为在接地板上刻蚀周期性的开口环得到。结果表明:圆形双开口环PBG结构简单易于实现,并且可以获得较宽的通带及较小的通带波纹。方形双开口环PBG结构具有良好的通带特性,并且可以有效地改善通带的平坦度,减小插损,适用于微波及毫米波集成电路。     

两种双负材料电磁参数提取方法的比较验证

双负材料电磁参数的准确提取是新型双负结构探索和双负材料应用研究中的关键问题.分析研究了基于散射参数以及近似解析表达式的双负材料电磁特性参数提取技术,给出了相应的计算公式.通过对金属丝单元、谐振环单元以及金属丝与谐振环组合单元异质填充结构的电磁散射参数的计算机仿真计算,提取出三种不同结构的电磁特性参数,并根据仿真结果对两种参数提取方法进行分析比较.研究表明:解析公式提取法可以准确的预测出谐振点的位置,S参数提取法提取的参数曲线则更接近实际情况.     

基于Simulink仿真的电动机变结构调速

为了改善直流电动机降压调速的动态特性,减小电枢电流脉动,文中提出一种直流电动机降压调速新方法,用双滑模面变结构控制DC-DC变换器进行直流电动机降压调速,利用双滑模面分别实现直流电动机内外环控制,内环滑模面用于电流控制环,外环滑模面用于转速控制环.通过Matlab中的Simulink工具仿真和比较表明直流电动机采用这种变结构控制降压调速,可得到平滑无级调速;其响应的上升时间、调整时间均很小;对外界扰动和参数摄动有很强的鲁棒性;电枢电流和电磁转矩冲击可控制在允许值内,具有理想的调速性能.该方法具有一定的实用价值.     

双层结构的无线无源柔性压力传感器设计

本文设计了一种双层结构的基于平面螺旋电感与叉指电容并联结构的LC谐振式无线无源柔性压力传感器。该传感器利用平面LC谐振回路的谐振频率随着外界应力的变化而改变的特性,采用电磁耦合的方式来实现对外部压力的无线测量。通过高频电磁仿真软件HFSS的建模与仿真,表明:该双层结构的传感器具有良好的压力测量特性,其有效测量距离达到了35mm,高于单层结构的测量距离(25mm),且可恢复性和重复性能良好,在电子皮肤和智能穿戴领域有着广阔的应用前景。     

太赫兹波段超材料在核酸恒温指数扩增检测上的应用

超材料对电磁场具有介电环境敏感和局域电场增强等奇特的电磁特性,近年来广泛用于无标记生物检测。文中设计并制作了一种金属开口谐振环阵列结构的超材料,在太赫兹波段下分别检测核酸恒温指数扩增前后反应体系,在氮气干燥环境下,扩增反应前后的频率偏移量分别为Δf1=（54±3）GHz、Δf2=（60±5）GHz。实验结果显示金属开口谐振环阵列结构的超材料可以作为一种生物传感器快速无标记检测核酸扩增前后的变化。     

互补开口谐振环微带传感器介电常数的测量

介电常数是材料的重要特性之一,采用互补开口谐振环微带传感器实现了不同厚度待测物质介电常数的无损测量。方形互补开口谐振环蚀刻在微带线接地平面上,与微带线耦合实现谐振,分析了谐振器的等效电路,讨论了介电常数与谐振频率之间的关系。通过有限元分析,谐振频率的负二次方与待测物质的介电常数实部值存在线性关系,且线性关系受待测物质的厚度影响;介电常数的虚部值对谐振频率的影响可忽略不计;最终建立了介电常数实部值与谐振频率和样本厚度之间的数学解析式。实验测试结果表明,当待测样品的厚度大于2 mm时,实部介电常数的相对测量误差小于3.5%。     

金属环境对谐振式无线电能传输系统的影响分析

根据磁耦合谐振式无线电能传输原理,建立两线圈的磁耦合谐振式电路模型,通过金属材料相对磁导率的引入,分析了不同金属环境对无线电能传输系统的自感、互感、传输效率的影响.采用Maxwell磁场计算软件计算无金属环境及不同金属环境下收发线圈参数,再利用Maxwell和Simplorer联合仿真分析电磁屏蔽效果;利用联合仿真探究了金属环境对系统传输特性的扰动并实验验证.铁磁性屏蔽板铁、镍的存在有效约束了空间磁场分布,具有很好的电磁屏蔽作用,减少电磁干扰;同时使得无线电能传输系统的收发线圈电感增大,而金属铜、铝环境中对无线电能传输系统几乎无影响,与无金属环境结果相同.最后通过实验验证实验结果与理论分析的一致性.     

基于CSRR的微带-共面波导型CRLH-TL

针对谐振器频带窄的问题,设计了一种新型的微带-共面波导型复合左右手传输线。利用缺陷地面结构(DGS)在微带线底板上蚀刻了矩形逆开环谐振器(CSRR),中心导带与上表面导带相互耦合形成左手电容,来设计CRLH-TL。利用传输矩阵法和Bloch-Floquet理论分析了传输特性和色散特性,并利用Ansoft HFSS高频仿真软件的传输特性进行了全波仿真。CRLH传输线单元尺寸为13.2mm,通带范围为1.1～5.6GHz,相对带宽为134%,属于超宽带左手结构。经仿真结果证明有较好的带通滤波性能,适合在微波器件中推广应用,促进左手材料在微波电路中的发展。     

Closed-form expressions for computer-aided design of microstrip ring antennas

This article presents closed-form expressions for the resonant frequency and radiation characteristics of microstrip ring antennas to assist in the computer-aided design of such antennas. Radiation fields are obtained using the vector electric potential calculated from the magnetic currents flowing along the inner and outer edges of the planar waveguide model for the microstrip ring structure. Expressions for radiated power, conductor and dielectric loss factors, resonant resistance, efficiency, and directivity are derived. The smaller the radius of curvature of the ring, the larger is the spacing between the magnetic currents flowing along the inner and outer edges and thus the radiation efficiency is higher. The effect of a dielectric layer covering the ring antenna is also included. Experimental results for the resonant frequency and the radiation patterns agree well with the theoretical predictions. © 1992 John Wiley & Sons, Inc.     

A broadband radar cross section reduction metasurface based on integrated polarization conversion and scattering cancelation

In this paper, we proposed and demonstrated a broadband radar cross section (RCS) reduction metasurface by integrating polarization conversion and scattering cancelation. A broadband polarization conversion structure was designed based on split concentric ring. We used a 4 × 4 array of split ring structure and its mirror‐symmetric structure as the super‐cell units to construct a metasurface with chessboard structure. The metasurface can efficiently reduce the co‐polarization RCS for all azimuth angles of incident wave. The metasurface sample with optimized structure parameters was fabricated and measured. The measured 10 dB RCS reduction band of the metasurface is from 8.6 to 17.7 GHz.     

Versatile CAD formulation for estimation of the resonant frequency and magnetic polarizability of circular split ring resonators

In this article, we propose a theoretical formulation to estimate the resonant frequency and magnetic polarizability of a circular split ring resonator (SRR). The computed results are compared with experimental and simulation results revealing excellent agreement for a wide range of frequencies. The proposed theory was compared with simulation for different parametric variation of the SRR. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

A novel dual‐band bandpass filter using co‐directional split ring resonators with closely spaced passbands and wide upper stopband

In this article, interdigital capacitor loaded co‐directional split ring resonators (CDSRRs) and their dual‐band bandpass filter applications are proposed. The proposed resonator is formed by nested open loop resonators having open ends at the same place unlike conventional split ring resonators (SRRs). In addition, the inner open loop resonator has interdigital capacitor located between the open ends. The proposed resonator exhibits dual resonance behavior with a small center frequency ratio. Both of resonance frequencies can be controlled due to the changes in the interdigital capacitor and the electrical length of the outer resonator. A dual‐band microstrip bandpass filter is designed by using the proposed CDSRR. Two CDSRRs are used to obtain two poles in each passband. Overall electrical length of the designed filter is 0.23 λ_g × 0.14 λ_g (0.0329 λ_g²), where λ_g is the guided wavelength for the used substrate at the lowest passband center frequency of 1.8 GHz. A small center frequency is obtained by adjusting the second passband at 2.27 GHz. A very wide upper stopband, closely spaced passbands, low insertion losses and high selectivity at both passbands can be obtained by means of the proposed structure. The designed filter was also fabricated and tested. The measured results show a very good agreement with the predicted results.     

Complementary metamaterial transmission line for monoband and dual‐band bandpass filters application

A novel composite right‐/left‐handed transmission line (CRLH TL) and its equivalent circuit model are proposed based on cascaded complementary single split ring resonator (CCSSRR). It features an intrinsically balanced wider band and an additional transmission zero above the right‐handed band relative to CRLH TL using complementary single split ring resonator and complementary split ring resonators. Moreover, two single negative (SN) metamaterial (MTM) TLs constructed by using complementary electric inductive‐capacitive resonator on the conductor strip and on the ground, respectively, are researched. Both SN MTM TLs exhibit electric resonance above the fundamental magnetic resonance. For application, a monoband (MB) bandpass filter (BPF) covered WLAN band, and a dual‐band (DB) BPF covered satellite DMB band and WiMAX band are designed, fabricated, and measured. The SN MTM TLs are adopted for the sake of deep and wide out‐of‐band suppression while CRLH MTM TLs using square‐shaped and Sierpinski‐shaped CCSSRR are critical factors of the MB and DB behavior. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

基于有限元的低风压导线结构分析

为降低导线表面风压,近年来国内外学者提出了多种截面形状的低风压导线,验证 了其工作机理。然而,鲜见涉及低风压导线结构稳定性、放线跳股问题的研究。为此,利用ANSYS 软件对架空线路中常用的钢芯铝绞线和低风压导线建立有限元模型,并结合导线放线时发生跳 股的判定依据,分析不同工况下,导线放线时的位移云图与结构稳定性,探讨最外层导线根数 与导线结构稳定性的关系。结果表明,低风压导线最外圈导线根数越多,导线结构越稳定。     

A low power micro fluxgate sensor with improved magnetic core

The influence of an improved magnetic core on the micro fluxgate sensor about sensitivity and power consumption is investigated and discussed in this paper. We have fabricated the micro solenoid fluxgate sensors based on the MEMS technologies, with the electroplating permalloy cores, which are easy to process and used in common; and the amorphous soft magnetic ribbon cores, which have better soft magnetic performances but be hard to be integrated, respectively. Four magnetic core structures are designed, including rectangular structure, unequal width rectangular structure, multi rectangular ring structure and spiral structure. Spiral structure can improve the performances of the fluxgate sensor significantly, both sensitivity and power consumption. The micro fluxgate sensors with the amorphous soft magnetic ribbon cores are promoted in all aspects than those with the electroplating permalloy cores, including ultra low power consumption of 2.4 mW with unequal width rectangular structure, and high sensitivity of 118 V/T with rectangular structure in wide linear range of 0–800 μT.