低成本宽带高效率堆叠贴片天线

为克服合成孔径雷达中现有微带天线带宽窄、效率低、成本高的缺陷,提出了一种在低成本FR4基板上实现的X波段宽带高效堆叠微带贴片天线。天线通过多层FR4基板堆叠方式构成,通过空气腔的引入,天线的有效介电常数和介质损耗得到降低,天线的效率和带宽得到提升。利用寄生贴片在带内增加了谐振点,使得天线的带宽得到进一步增大。同时为补偿馈电探针的寄生电感,利用微带匹配器对天线的输入阻抗进行匹配。实测表明,天线输入驻波低于2.0的频率范围为7.7~11.7GHz,相对带宽大于40%。天线的增益为7.6dBi,效率为83%。与传统微带贴片天线相比,具有宽带、高效、低成本的特点,具有一定应用前景。     

共面波导馈电的超宽带天线研究

设计了一种共面波导馈电的超宽带(UWB)天线,其阻抗带宽达到341%。所设计的天线印刷在尺寸为28mm×21mm×1.6mm,介电常数为2.65的聚四氟乙烯介质基板上。同时为了实现该天线与WLAN(5.725~5.825GHz)系统的协同工作,本文在共面波导的地面上刻蚀一个矩形槽,实现UWB与WLAN系统的兼容。利用高频结构仿真软件HFSS对影响天线性能的主要物理参数进行仿真、分析和优化,得到天线的优化尺寸。实验结果表明,该天线比传统微带贴片天线性能有了较大的提高,从而表明了利用共面波导馈电和刻蚀矩形槽的天线设计方法实现多种宽带通信系统兼容的可行性和有效性。     

表面开槽的宽带遥测微带天线设计

微带天线由于体积小、易共形、适用于金属环境等优点而被广泛地应用于旋转件遥测系统中。针对传统微带遥测天线带宽较窄的问题,本文提出了一种通过在天线贴片和地板上开槽来扩展带宽的设计方法,并进行了仿真和测试验证,二者结果吻合良好。高频电磁结构仿真软件HFSS的仿真结果表明,通过在适当位置开槽,可使得天线的相对阻抗带宽(S11<-10dB)达到5.6%(2.409~2.545GHz),基本覆盖ISM频段,最高增益可达4dBi。测试结果表明其相对阻抗带宽为6%(2.41~2.56GHz),在收发天线间距10毫米的情况下,传输系数S21达到-22dB,可以满足遥测系统的需求。     

PBG结构圆柱形微带贴片天线的设计与仿真

本文利用光子晶体带隙(PBG)结构的特点,将特殊设计的 PBG 结构应用于圆柱形微带贴片天线中。在同轴线馈电的圆柱形微带贴片天线的介质上蚀刻出按一定规律排列的 PBG 结构,并基于 HFSS 对特殊设计的 PGB 结构圆柱形微带贴片天线和普通的圆柱形微带贴片天线进行仿真和优化,仿真结果表明,按照一定规律排列的 PBG 结构可以有效抑制天线表面波的传播,明显提高圆柱形微带贴片天线的带宽和增益,有效改善圆柱形微带贴片天线的辐射方向图,实现天线性能的优化设计。     

一种新型双频微带天线的设计与仿真

本文研究了一种新型结构的可同时工作在S/X波段的双频微带贴片天线.该天线的S波段单元和X波段单元印制在同一层介质基板上,S波段单元是一在边长40 mm方形贴片内对称开出4个边长12 mm方形槽的"田"字形贴片天线,4个边长为8 mm的方形贴片对应布置于"田"字形贴片槽内.这种结构可以实现天线的孔径复用,有利于减小天线的尺寸重量,便于设计制造.最后借助Ansoft 公司的Designer仿真软件对此天线进行仿真计算,讨论了两种情况下天线的辐射特性.     

倒置微带贴片谐振器测量汽轮机湿度的研究

汽轮机蒸汽湿度的在线测量,对汽轮机的安全、经济运行具有重要的理论意义和实用价值。根据微扰法的基本理论,提出一种结构简单、灵敏度高的倒置微带贴片谐振器,实现汽轮机湿度的准确在线测量。湿蒸汽的湿度变化反应为谐振器介质层介电常数的变化,根据微带贴片谐振器的基本原理,仿真计算不同介电常数下的谐振频率,得到其变化关系曲线;讨论样本厚度、基质厚度和基质介电常数对频率偏移量的影响;设计微带贴片谐振器模型,并分别在HFSS和CST软件下进行仿真。研究及仿真结果表明,微带贴片谐振器模型适用于汽轮机蒸汽湿度的在线测量,蒸汽湿度每变化1%,谐振器频偏约为18 k Hz,约为微带缝隙谐振器频偏的3.6倍,有利于蒸汽湿度的准确测量。     

微带线不连续性辐射研究

分析了微带不连续性辐射的基本原理,采用FDTD方法和坡印廷矢量法相结合,研究了拐角、短截线等微带不连续性的辐射特性,对微带不连续性和微带贴片天线的辐射机理进行了比较。仿真结果显示,不连续性表面波和空间波辐射损耗随着频率的增加而显著增大,低频时辐射损耗以空间波辐射为主,高频时表面波辐射有超过空间波的趋势。微带短截线的谐振辐射特性与矩形微带贴片天线类似,只是在辐射强度上有较大的差别。     

一种新型端射天线单元的研究

设计了一种新型的端射天线单元。采用独特的串馈单极子形式，具有较好的带宽性能，基板采用液晶材料，使其基板的介电常数可控。通过改变单元的工作频率及基板的介电常数，使得天线单元具有水平相扫的能力。采用上下双层对称结构来抑制由于地板引起的波束上翘。通过对端射天线单元的建模仿真，验证其可行性。这样，串馈形式的天线易于实现天线的小型化、轻薄化。具有很好的共形的能力，适用于机载等高速运动的平台。     

具有方向图可重构特性的小型化天线设计

设计了一款具有方向图可切换特性的新型平面圆形可重构天线。该天线制作于介电常数为4.4的 RR-4介质板上,半径为60 mm,在x-o-y 平面上紧凑对称,具有低剖面、低成本、小型化的优点。天线可用阻抗带宽为2.36~2.51 GHz,可以适用于 Wibro,Bluetooth和 WLAN系统。通过改变不同辐射单元与馈电微带的连接关系,天线可在6个方向上实现波束可重构。若结合快速切换开关系统,天线可在x-o-y 平面上完成方向图电扫描。同时,测量和仿真结果具有很好一致性。     

一种大带宽高增益微带天线的研究与设计

普通微带天线带宽很窄,大多数扩展其带宽的方法是以牺牲天线增益为代价的.本文提出了一种新型大带宽、高增益微带天线结构.该天线采用厚的空气介质层,通过与贴片相连的斜置金属带进行馈电.此外,还采用了U形接地板来提高天线的增益.利用HFSS仿真软件计算和分析,探讨了各结构参数的变化对天线性能的影响,给出了详细的设计过程.仿真结果表明,该天线在驻波比小于2 时的相对带宽可达75.5%,在整个频带内的平均增益为7.31 dBi,而且,方向图和增益随频率变化较平稳.     

Analysis and design of rectangular microstrip antenna on two-layer substrate materials at terahertz frequency

In this paper, an effective permittivity of the two-layer dielectric substrate material has been analyzed to enhance the electrical performance of the rectangular microstrip patch antenna at terahertz frequency. The frequency dependent effective dielectric permittivity of the substrate materials has been evaluated and result has been compared with finite integral technique based CST Microwave Studio a commercially available simulator. The input impedance characteristic with electrical performance of the rectangular microstrip patch antenna on two-layer substrate materials has also been analyzed at 600 GHz. Manipulation in the input impedance characteristic of the antenna has led to a slow wave structure. This slow wave structure has been examined at 542 GHz, and improvement in the performance has been observed without increasing the overall dimension of the proposed antenna.     

Analysis and design of terahertz microstrip antenna on photonic bandgap material

In this paper, a dielectric slab with periodic implantation of the air gaps has been analyzed. An effective dielectric permittivity of the 1-D photonic bandgap substrate material (PBG material) with host material as Polytetrafluoroethylene (PTFE) has been computed at 600 GHz. Based on the extracted effective dielectric permittivity, a rectangular microstrip patch antennas on thin and thick 2-D PBG material as substrate have been designed. The electrical performances of the antennas have been simulated by using two different simulators, CST Microwave Studio based on the finite integral technique and Ansoft HFSS based on the finite element method. This proposed antenna on the PBG material as substrate shows the significant enhancement in the directivity. To validate the homogenized medium approximation, the effect of the antenna position on the substrate material has been observed. The response of antenna has been found to be independent of its position. Various electrical parameters of the proposed antennas have been compared with reported literature. In addition to this, the operating frequency of one of the antenna has been scaled down by the factor of 50 and its various results have been compared with the results obtained at 600 GHz.     

Modeling the superconducting effects on resonance and radiation characteristics of a cylindrical-rectangular microstrip antenna covered with a dielectric layer

In this work, the resonance and radiation characteristics of a superconducting cylindrical-rectangular microstrip antenna covered with a dielectric layer are studied using an electric field integral equation and the spectral-domain Green’s function. The effect of superconductivity of the patch is modeled by including surface complex impedance in the formulation. In order to validate the present method, numerical results for the cylindrical microstrip antenna with a perfectly conducting patch are presented and very good agreement has been demonstrated between our computed data and those found in the literature. Once the validity of the method is checked, the effect of the superconducting patch on resonance frequency, half-power bandwidth and radiation pattern of cylindrical rectangular microstrip patch is studied. It is found that the resonant frequency is affected significantly by the superconductivity property of the patch and the half-power bandwidth is considerably increased, which improves the narrow bandwidth characteristics of the microstrip structure. Further results show that a thin superconductor patch has a significant effect on the E-plane radiation pattern.     

Enhancement of microstrip antenna directivity using double-superstrate configurations

In this paper, the directivity of microstrip patch antennas with double-layer superstrate is investigated. Two dielectric superstrate layers, each a quarter wavelength in thickness and separated by an air gap, are introduced above the microstrip patch, separated by another air gap. The parameters of these layers are used as key controllers of the directivity enhancement. Numerical results indicate that the directivity increases significantly even with moderate superstrate dielectric constants when the double-superstrate configuration (DSC) is used. To demonstrate how the layers affect the directivity, an infinite dielectric model is first used. Then the effect of the superstrate transverse dimensions is studied by means of a finite dielectric model. The directivity variations with respect to frequency are compared for different superstrate surface areas. This work leads to the conclusion that modification of the superstrate transverse dimensions can optimize both directivity and bandwidth. The experimental investigations of DSC are also provided to support the simulation results.     

宽频带的微带等角螺旋天线设计

为了实现宽频带天线指定方向的高性能辐射，设计了一种宽频带的微带等角螺旋天线。为实现阻抗匹配，天线馈电部分设计了一种指数渐变式微带巴伦结构。经过实物测试参数，结果表明加入了指数渐变巴伦结构后天线实现了良好的阻抗匹配并具有良好的宽频带特性，其工作带宽为1.74～4.82 GHz，回波损耗最低达- 30 dB。同时设计了一个平底型金属反射腔用于反射背向电磁波，在保持宽频带工作特性的同时，使天线具有了良好的单向辐射特性，天线在整个工作频段内的增益均大于6 dB，与传统的螺旋天线相比，具有宽频、定向、高增益的特点，具有一定应用前景。     

Analysis and design of enhanced directivity microstrip antenna at terahertz frequency by using electromagnetic bandgap material

In this paper, an electromagnetic bandgap (EBG) material in the range of 0.5–0.8 THz has been simulated with Arlon AR 600 (ε=6.0) as host material and air‐cylinders as the foreign embedded material. The effective dielectric permittivity of this material has been analyzed at the frequency range of 0.590–0.620 THz. The reduced effective dielectric permittivity substrate of thickness 50 µm has been used to design the microstrip antenna at 600 GHz with a novel approach. This proposed antenna shows an enhanced directivity of 15.1 dBi at 600 GHz frequency. To compare the analysis, the operating frequency has been scaled down by a factor of 100 and various results have been compared by using two different commercially available simulators CST Microwave Studio based on the finite integral technique and Ansoft HFSS based on the finite element method. Copyright © 2010 John Wiley & Sons, Ltd.