基于MEMS开关的方向图可重构天线的设计

设计了一种波束可重构天线,以实现宽带、宽角方向图可重构设计。该天线由4组具有不同波束指向的天线子阵组成,通过6个RF-MEMS开关控制其波束指向;采用的宽带单元天线,在2.4 GHz～3.4 GHz频率范围内(相对带宽34.5%),电压驻波比小于2。馈电网络的设计采用小型化宽带阻抗变换器,减小了馈电网络尺寸,并拓展了带宽。仿真结果表明,可重构天线实现了0°,25°,40°和50°的不同波束指向,除部分频点外,4种状态天线的驻波在2.5 GHz～3.25 GHz(相对带宽26%)带宽内驻波比均小于2。     

Broadbanding of a Planar Antenna with Three Frequency Bands and Its Application

This paper describes a line element planar antenna with three frequency bands. To obtain broadband characteristics, a modified planar antenna that has semielliptical elements based on the characteristics of a line element planar antenna is proposed and analyzed by the finite difference time domain method. Return loss characteristics are discussed as functions of the eccentricity values of semi‐ellipse at each element. The broadbanding of the modified planar antenna is implemented based on the results. The planar antenna with three systems (an 800 MHz band cellular phone, a third‐generation cellular phone, and a 2.4 GHz band wireless LAN system) is considered as an application example.     

A loaded antenna system applied to VHF portable communication equipment

The technique of impedance loading to the antenna element has been applied to an antenna system for portable VHF communication equipment and its practical usefulness has been shown with a brief theoretical analysis and some experimental results. By means of impedance loading to the antenna element, the driving point impedance may be varied so as to make matching feasible, even though the element length is very short, and the effective length may be increased, so that the gain of the loaded antenna system relative to a non-loaded antenna system may be increased. As a practical example, an inductance loaded antenna system has been applied to a 34-54 MHz range portable communication equipment and about 5 dB relative gain increase has been observed.     

X波段共面波导结构串馈天线的设计

介绍了共面波导天线的辐射原理,在此基础上依据串馈天线理论设计出一种共面波导结构的串馈天线。天线辐射单元由6个微带单元串接组成,辐射单元与上地面之间的缝隙为恒定值,各个辐射单元的辐射系数由泰勒加权法确定,各个辐射单元的辐射能量逐次递减。经仿真计算回波损耗小于15 dB时,天线带宽为260 MHz(10.45~10.71 GHz),天线辐射主瓣与最大旁瓣差大于16.5 dB,天线的辐射效率为69%。     

A back-to-back rectangular-patch antenna fed by a CPW

The configuration of a back-to-back rectangular-patch antenna fed by a coplanar waveguide (CPW) is proposed. The characteristics of the proposed antenna element were clarified by experiments. The radiation patterns and input impedances were measured as parameters of the widths of the rectangular patch and the substrate. Experimental results for an array antenna using the proposed back-to-back rectangular-patch antenna element are described. Good omnidirectional radiation patterns and input impedance characteristics were obtained. The proposed array antenna is suitable for microcellular, wireless LAN, and indoor radio systems     

一种新颖的宽带高增益车载全向天线

介绍了一种工作在225～800MHz的双锥柱形超宽带垂直极化全向天线结构。在两天线单元之间加同轴电缆扼流圈替代传统的0．25A0扼流杯,并在天线底部加同轴电缆扼流圈和用Г匹配方式给两天线单元馈电的方法,完成了一种具有4个倍频程的超宽带垂直极化全向天线。该天线具有良好的匹配性能和辐射特性,有效的克服了一般超宽带全向天线垂直面辐射方向图主波瓣容易偏离水平面的不足。     

一种Ka/Ku双波段双极化共口径阵列天线

由于运载能力及卫星平台的限制,星载雷达要求雷达天线具有重量轻、功耗低、体积小、效率高等特点,尤其是对天线口径面积限制较为苛刻,双频段天线要想适用于星载条件,就必须考虑全新的结构形式。介绍了一种适应于星载条件的Ka/Ku双波段双极化共口径阵列天线,其中Ku波段天线双极化工作、Ka波段天线单极化工作。Ku波段天线阵采用了具有两阶零点滤波性能的微带耦合馈电辐射缝隙单元,这种天线单元具有易实现双极化、工作频带宽等优点。Ka波段天线阵采用侧馈微带帖片天线单元,其优点是易于实现与Ku波段天线共孔径。     

Theoretical analysis and some experiments on Vierergruppe Antenne (Two-dipole antennas)

A center-fed full-wave dipole antenna located one-quarter wavelength above a reflecting plate has a very low potential relative to the plate, at the center of each half-wave element. When metal support bars are attached between these center points and the reflector plate to support the antenna, the structure is called a "metal supported full-wave dipole antenna." An antenna made up of two such full-wave dipole antennas has four half-wavelength antenna elements and has been named "Vierergruppe Antenne." This antenna and the "Achterergruppe Antenne" were invented in Germany. Vierergruppe antenne (sometimes called two-dipole antennas) can be rugged because they are made entirely of metal and do not require insulator supports. They also have excellent electrical characteristics over a very wide frequency range, and are widely used by TV and FM broadcasting stations around the world. Since the full-wave dipole antenna element is composed of a conductor having a diameter as large as 1/20 of the operating wavelength, it is unsuitable to use conventional thin conductor theory to analyze the antenna behavior. In particular, the current at the end of the thick solid antenna element will not be zero, as in the case of the thin one. Flat end-face currents are determined by using a quasi-static approximation and the moment method of analysis. Accordingly the excellent characteristics of this antenna have been found theoretically and fully clarified in the quarter century since its invention.     

Active Frequency-Tune Beam-Scanning Leaky-Wave Antenna Arrays

X-band active beam-scanning leaky-wave antenna arrays, including 1 × 1,1 × 2 and 1 × 4 prototypes, have been demonstrated. These antennas integrated one or several microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Measured results on experimental antennas indicate that the beam scanning angle of the 1 × 1 antenna close to 40° can be achieved and the scanning range of 1 × 2 and 1 × 4 antenna arrays are both close to 32°. Furthermore, reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array and the antenna efficiency increases. When comparing with the measured radiation pattern of the single element antenna, we found that the 1 × 2 and 1 × 4 antenna arrays can effectively suppress the reflected power by more than 5.5 dB and 10.5 dB, respectively, at 10.2GHz. The power gain are more than 2 dB and 3.16 dB higher than the single element antenna with a measured EIRP of 18.67 dBm.     

低雷达截面的超宽带扇形天线

 本文研制了一种新型可用于低可见平台的超宽带扇形天线.该扇形天线利用由一个矩形条带和对称分布在该矩形条带上的8个圆弧条组成的扇形结构设计天线的辐射单元;利用两边倒有90度圆弧角的矩形设计辐射地板;并将辐射单元和辐射地板分别印制在FR-4介质材料板(介电常数为4.4)的两侧.研究天线的辐射和散射特性,并与参考天线作对比,发现在满足超宽带天线的相关指标要求下,本文提出的天线具有良好的雷达截面减缩效果.本扇形天线适用于对超宽带天线有低雷达截面要求的场合.     

抗干扰天线及天线阵列研究

本文对抗干扰天线及天线阵列进行了研究,提出了一种小型化的微带贴片天线,并使用该天线单元进行组阵。文中提出的立体天线阵列的主天线单元实现了宽波束和在低仰角方向上增益的改善,能够满足工程应用的需要。     

考虑互耦的阵列天线辐射近场近似计算方法

针对大规模阵列天线辐射近场电磁兼容性问题,基于有源单元方向图原理和子阵信息的综合方法计算了大规模阵列天线辐射近场场强的分布。该方法采用等效技术获取大规模阵列天线的端口特性,进一步结合天线单元的远场数据综合分析得到大规模阵列天线的近场分布;计算结果表明,在满足天线单元辐射远场条件下,该方法能够准确计算出大规模阵列天线的辐射近场分布。相较于全波分析,本方法在保证精度的同时,提高了计算效率,并且具有良好的灵活性。通过全波分析的数值算例验证了该方法的正确性。     

数字阵雷达天线波瓣图测试方法与试验验证

针对固定式相控阵雷达在中场法或远场法中不能实时得到天线波瓣图的问题,提出了采用扫描波瓣图替代天线波瓣图进行天线测试的方法。从理论上分别推导了和波束与差波束扫描波瓣图和天线波瓣图的解析式,研究了单元波瓣图对扫描波瓣图和天线波瓣图的影响,指出了在单元波瓣主瓣范围内扫描波瓣图和天线波瓣图近似等价。仿真和试验结果 均表明:扫描波瓣图和天线波瓣图在各项性能指标上都是等价的,可用于指导雷达总体依据扫描波瓣图对天线进行验收。     

Mesh antennas for dual polarization

Three mesh antennas, all having an extremely small antenna height of approximately 0.06 wavelength above a ground plane, are presented. First, a mesh antenna excited with a balanced feed is analyzed. It is revealed that the mesh antenna radiates a linearly polarized wave with no cross-polarization component in the principal planes. The radiation mechanism is explained using the current distribution. Second, a mesh antenna excited with an unbalanced feed is analyzed. This antenna shows almost the same radiation characteristics as the mesh antenna with a balanced feed. The frequency bandwidth for a VSWR=2 criterion is evaluated to be approximately 3%. Third, a mesh antenna having two perturbation elements is analyzed. It is found that the antenna acts as a radiation element of circular polarization. The frequency bandwidth for a 3-dB axial ratio criterion is calculated to be approximately 1%. The mesh antennas in the first and second analyses can be used as dual linear polarization elements by appropriately switching the feed. Similarly, the mesh antenna in the third analysis can be used as a dual circular polarization element by switching the feed     

便携设备中带陷蝶形UWB天线的设计

提出了一种应用于便携设备中具有带陷特性的平面蝶形UWB天线.该天线采用蝶形贴片作为辐射单元,并由渐变线作为阻抗变换器与50 Ω馈线进行匹配.通过在辐射面上挖C形槽实现带陷功能,并给出仿真和实测结果.该天线的工作频带覆盖3.1～10.6 GHz,并有效避免了5.15～5.825 GHz的无线局域网(WLAN)频段,适于便...     

一种宽带宽角双极化相控阵天线单元研究

设计了一种宽带宽角双极化相控阵天线单元,该天线单元采用指数渐变开槽天线形式,并设计了金属匹配柱安装在双极化天线单元之间,保证了开槽天线的接地连续问题。依次给出了该双极化天线单元的仿真设计、阵列样机的性能测试,从仿真和测试结果中可以看出,该双极化天线在3倍频程带宽内具有良好的匹配和辐射特性,并且能实现大角度二维扫描。该双极化天线单元具有宽频带、体积小、结构简单等特点,适于用作宽带宽角扫描相控阵天线的阵列单元。     

Compact and miniaturized microstrip antenna based on fractal and metamaterial loads with reconfigurable qualification

We have described a compact antenna based on fractal and metamaterial loads techniques. The microstrip patch antenna is assumed as a basic antenna and then the effect of fractal structures is implemented. The fractal patch is considered as a right-handed element and then by adding a left-handed element, the antenna miniaturization is achieved by using the metamaterial loads technique. The equivalent circuit is also used to describe the element effect on miniaturization and parametric models clarify them. The proposed antenna is modified for wireless applications and experimental results confirm our simulation results. In addition, we show that the proposed antenna is suitable for reconfigurable. By joining the unit cells together with various arrangements and changing the effective length, the various inductances can be obtained. Finally, by adding reconfigurable characteristic to the proposed antenna, the gain and radiation pattern can be controlled as shows in this paper. The patch antenna has low bandwidth and gain and so we have developed the patch antenna with defected ground to improve the bandwidth and the Frequency Selective Surface (FSS) is used to achieve higher gain and bandwidth. The final antenna is covering 2.4, 3.5 and 5.5 GHz with higher gain than the patch antenna.     

某碳纤维天线的结构设计及模态分析

从保证天线的强度、刚度以及反射面精度等几个方面,介绍了某碳纤维复合材料天线的结构设计,并用有限元分析软件ANSYS10.0对该雷达天线进行了模态分析,得到了该天线的固有频率,确保满足系统对该天线抗振性能的要求。     

Photodiode-integrated microstrip antenna array for subterahertz radiation

The radiation characteristics of subterahertz (sub-THz) electromagnetic waves emitted from an antenna array integrated with photodiodes are investigated. The element of the fabricated array antenna was a 300-GHz microstrip antenna integrating a uni-traveling carrier photodiode. It was observed that the beamwidth of a 3 /spl times/ 1 antenna array is about half that of the single microstrip antenna. We also confirmed that the radiation direction changed by 20/spl deg/ when 2/spl pi//5 of phase difference was added to the input optical signal for each antenna element. These results demonstrated that sub-THz waves emitted by each element of the array were coherently superimposed and the power combining of the sub-THz radiation occurred in the microstrip antenna array. The measured output power of each radiation element is about 120 /spl mu/W, and a total output power of 1 mW can be estimated for a fabricated 3 /spl times/ 3 array in an ideal radiation condition.     

Design and development of a unit element microstrip antenna for aircraft collision avoidance system

Aircraft/traffic alert and collision avoidance system (ACAS/TCAS) is an airborne system which is designed to provide the service as a last defense equipment for avoiding mid-air collisions between the aircraft. In the existing system, four monopole stub-elements are used as ACAS directional antenna and one blade type element is used as ACAS omnidirectional antenna. The existing ACAS antenna has some drawbacks such as low gain, large beamwidth, frequency and beam tuning/scanning issues etc. Antenna issues like unwanted signals reception may create difficulties to identify the possible threats. In this paper, the focus is on the design and development of a unit element microstrip antenna which can be used for ACAS application and to overcome the possible limitations associated with the existing techniques. Two proposed antenna models are presented here, which are single feed and dual feed microstrip dual patch slotted antenna. These are designed and simulated in CST Microwave Studio tool. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. A good reflection coefficient, Voltage Standing Wave Ratio (VSWR), narrow beamwidth, perfect directional radiation pattern, high gain and directivity make this proposed antenna a good candidate for this application.