一种新型双频宽波束四臂螺旋天线的设计

根据移动卫星通信和卫星导航定位中对天线宽波束、圆极化和低仰角增益等要求,设计了一种新型的双频四臂螺旋天线,通过将工作于不同频段的两副结构类似的天线以内外共轴的方式形成一个整体来实现双频工作。天线通过开槽线巴伦实现平衡馈电,利用四臂螺旋自身的结构特点构造了90°自相移结构,获得了较好的宽波束圆极化特性。测试结果表明。实测和仿真结果基本一致,天线在两个频段都实现了较好的宽波束圆极化特性。     

Aircraft measurements of the microwave scattering signature of the ocean

Microwave scattering signatures of the ocean have been measured over a range of surface wind speeds from 3 m/s to 23.6 m/s using the AAFE RADSCAT scatterometer in an aircraft. Normalized scattering coefficients are presented for vertical and horizontal polarizations as a function of incidence angle (nadir to55deg) and radar azimuth angle (0degto360deg) relative to surface wind direction. For a given radar polarization, incidence angle, and azimuth angle relative to the wind direction, these scattering data exhibit a power law dependence on surface wind speed. The relation of the scattering coefficient to azimuth angle obtained during aircraft circles (antenna conical scans) is anisotropic and suggests that microwave scatterometers can be used to infer both wind speed and direction. These results have been used for the design of the Seasat-A Satellite Scatterometer (SASS) to be flown in 1978 on this first NASA oceanographic satellite.     

Deep-space antenna for Rosetta mission: design and testing of the S/X band dichroic mirror

The paper presents the design, fabrication, and testing of a dichroic mirror to be operated in the deep-space antenna of the European Space Agency in Perth, Australia. The dichroic mirror is designed for combining the signals in the S and X bands in the beam-waveguide feeding system of the 35 m reflector antenna. The final design consists of a thick metal plate of 2.5 m in diameter, perforated periodically with rounded cross-shaped holes. The design of such a structure required a trade off between electrical, mechanical, and technological constraints. The design and testing of a validation sample as well as of the final mirror are discussed.     

基于CSRR结构的低RCS 微带天线设计*

基于互补开口谐振环奇异的折射率特性,研制了一种可用于雷达低可见平台的新型微带天线.采用等效分析方法对CSRR结构的等效媒质参数加以研究,并将其应用于普通微带天线非辐射边一侧的接地板上,在保证天线辐射特性基本不变的同时使散射波远离镜像方向,从而实现在空域中的带外雷达散射截面积减缩.仿真和测试结果表明,加载CSRR结构的微带天线仍为线极化,前向增益仅损失0.32dB,对于不同角度入射波镜像方向RCS均有减缩,其中法线方向RCS最大减缩量达到7.8dB.该设计具有低成本、设计简单、便于加工、利于共形等优点,为天线RCS减缩提供了新思路.     

19 GHz space-Earth depolarization measurements at 4° polarization

Depolarization was measured at a polarization angle of4degfrom vertical. Depolarization transformed to this4degpolarization from measurements made at polarizations21degfrom vertical and horizontal is compared with the direct measurements scaled to the path elevation angle of the transformed measurements. Over the ranges of attenuation and depolarization for which the measurements are meaningful, the agreement between them is good. These results further reinforce our confidence in the results and conclusions obtained earlier using the polarization transformation technique.     

Dual-frequency planar inverted-F antenna

Cellular telephone handsets are now being designed to have dual-mode capabilities. In particular, there is a requirement for internal antennas for GSM and DCS1800 systems. This paper describes a novel planar dual-band inverted-F antenna for cellular handsets, which operates at the 0.9-GHz and 1.8-GHz bands. The dual-band antenna has almost the same size as a conventional inverted-F antenna operating at 0.9 GHz and has an isolation between bands of better than 17 dB. The bandwidths of the antenna are close to those required for the above systems. Good dual-band action is also obtained for other frequency ratios in the range of 1.3-2.4. Studies also show that the dual-band antenna can operate with one or two feeds. A finite-difference time-domain analysis has been shown to give calculated results close to those measured     

一种双宽带雷达散射截面减缩的超表面设计方法

超表面由于其灵活的电磁波调控能力而受到广泛关注,基于其在雷达散射截面(radar cross section, RCS)减缩设计中受限于工作频带单一、设计通用性低的问题,文中提出一种新型的叠层型超表面设计方法,来灵活实现双宽带的RCS减缩. 首先设计了工作在两个频带且具有极化旋转特性的超表面结构及低通频率选择表面(frequency selective surface, FSS),并将其与两个极化旋转超表面相集成,形成了具有双频带极化旋转特性的超表面结构;然后基于极化相消原理,将该阵列进行旋转排布,形成2×2的阵列结构,以实现在6.6～12.7 GHz和27.8～38.1 GHz两个频带内?10 dB的RCS减缩. 对所设计的超表面结构进行实物加工,实测结果与仿真结果对比吻合良好,从而验证了双带RCS减缩的良好特性.     

Tunable dual-band planar antenna

A dual-band antenna design that covers the 2.26-2.54 GHz and 5.14-6.10 GHz bands is presented. The proposed antenna design consists of two patch radiators suspended above a ground plane. The performance in the lower and upper bands can be controlled with less mutual coupling effect. The antenna also features less beam squinting of the radiation patterns at boresight for both operating bands.     

Miniaturised reconfigurable window slot antenna using mechanical tuning

A novel design approach of varying the slot width on radiating patch of a microstrip antenna for achieving reconfigurable dual-band operation is proposed. The design of this miniaturised reconfigurable antenna is done without the use of active switches or MEMS. The dual band is obtained by rotating the strips on the patch creating slots and varying the slot width using mechanical tuning. The strip is rotated in angular position from 0° to 90° varying the slot width that alters the resonant frequency of the antenna making it resonate at different frequencies covering the wireless bands for global system for mobile communication, global positioning system, wireless local area network and Bluetooth. This antenna provides a dual-band operation that shifts over the bands depending upon the slot width. This antenna achieves the bandwidth requirement and gain in the bands of operation. The effect of change in slot width on the radiation pattern is also discussed. The prototype antenna is fabricated and tested to prove the proposed concept of design. The measured results are in agreement with the simulated results.     

An experimental completely overlapped subarray antenna

A completely overlapped subarray antenna was designed, fabricated, and tested to demonstrate its broad-band, low sidelobe, wide scan angle performance. It uses time delay steering at the inputs to a transform feed, which illuminates a phase-shifter steered objective lens. The transform feed is a Rotman lens and the objective is a cylindrical bootlace lens, both of which are parallel plate waveguide cavities with coaxial probe elements. The signal bandwidth goal of 20 percent (8.1-9.9 GHz) at55degscan was met easily, however, achieving the peak sidelobe goal of - 30 dB proved more difficult because of internal reflections in the Rotman lens beamformer. A brief summary is presented of the completely overlapped subarray antenna (COSA) concept to explain the detailed design of our experimental model. Antenna pattern and S-parameter measurements illustrate the operating principles, the difficulties encountered, and the results achieved.     

等离子体天线原理与设计

等离子体天线因具有隐身、动态重构、超宽带等优点,可广泛应用于多功能雷达、电子对抗等军事技术领域。等离子体天线主要包括等离子体柱形电介质天线和反射面天线2种形式。基于表面波在等离子体中的传播特性,给出了柱形等离子体天线系统设计;基于等离子体反射电磁波特性,给出了反射面等离子体天线系统设计,为等离子体天线技术趋于实用化提供了必要的理论及技术准备。     

A dual-band CP dual-orthogonal arms monopole antenna with slanting edge DGS for C-band wireless applications

This communication describes a novel design of circularly-polarized (CP) monopole antenna for dual-band performance. The proposed design offers an impedance bandwidth (IBW) of 3.7 GHz in the frequency range 2.9–6.6 GHz in the lower band and 1 GHz (7.7–8.7 GHz) in the upper band. Proposed antenna has a wide CP (3 dB axial-ratio) bandwidth of 2.42 GHz (46.6%) in lower band (4.08–6.5 GHz) and 300 MHz in upper frequency band (8.1–8.4 GHz). The CP bandwidth is achieved through dual orthogonal arms and slanting edge defected ground structure (DGS). Proposed antenna is suitable for the C-Band wireless applications including WLAN, Wi-MAX communication systems.     

Frequency scanning by leaky-wave antennas using artificial dielectrics

Frequency-scanning characteristics of an artificial dielectric leaky-wave antenna are discussed. It is experimentally observed that the beam angle changes from10degto50degoff broadside when the frequency is changed from 8.13 to 9.05 GHz. Over this frequency range the beamwidth does not vary monotonically and changes from7.5degto6.0degto7.1deg. It is found that the artificial dielectric antenna has a better temperature stability than that for frequency scanned arrays.     

一种新型双频天线的设计与仿真

本文使用一类新型的天线双频实现方法,设计和仿真了一种工作在600MHz/1800MHz 的双频天线。从振子天线、 Vivaldi 天线的工作原理出发,结合镜像原理完成了本天线的设计。而后,分别利用HFSS 和CST 微波工作室对天线进行 建模仿真,得到了良好的双频性能,同时也验证了设计思路的正确性。     

Modified inverted-L monopole antenna for 2.4/5 GHz dual-band operations

A novel compact modified inverted-L monopole antenna for dual-band operation is proposed. The proposed antenna is designed to operate in 2.4 GHz (2400-2484 MHz) and 5 GHz (5150-5825 MHz) bands for WLAN applications in IEEE 802.11a/b and HIPERLAN/2 systems. The method to realise the desired dual-band operation is by introducing a meandered wire and a conducting triangular section to a conventional inverted-L monopole, which results in a small antenna size of 7/spl times/18 mm/sup 2/. Good impedance bandwidth performance is also observed.     

FDTD方法分析新型双频平面倒F手机天线

设计了一种新型单馈点双频平面倒F手机天线(PIFA),用时域有限差分方法(FDTD)计算了该天线的电流分布和辐射方向图,以验证设计原理。该天线可用于GSM和DCS1800两个系统,中心工作频率分别为0.94GHz和1.8GHz,反射损失小于-10dB的阻抗带宽可达到10％以上。通过简单调节天线的两个参数,天线两个频段的中心工作频率独立可调,来消除手机设计制造误差对天线工作频率的影响。     

多波段共面天线的研究

跟踪测量雷达因其精度要求,波束宽度很窄。为实现雷达自引导功能,本文介绍了一种跟踪测量雷达的多频段共面的天线技术,重点对共面天线设计、组合馈源设计以及双频段自引导概率计算进行了论述,并给出了一些设计实例和仿真计算结果。结果表明:多频段天线的应用完全可用一部雷达取代两部或两部以上的雷达。     

A Novel Dual-Band Printed Diversity Antenna for Mobile Terminals

A novel dual-band printed diversity antenna is proposed and studied. The antenna, which consists of two back-to- back monopoles with symmetric configuration, is printed on a printed circuit board. The effects of some important parameters of the proposed antenna are deeply studied and the design methodology is given. A prototype of the proposed antenna operating at UMTS (1920-2170 MHz) and 2.4-GHz WLAN (2400-2484 MHz) bands is provided to demonstrate the usability of the methodology in dual-band diversity antenna for mobile terminals. In the above two bands, the isolations of the prototype are larger than 13 dB and 16 dB, respectively. The measured radiation patterns of the two monopoles in general cover complementary space regions. The diversity performance is also evaluated by calculating the envelope correlation coefficient, the mean effective gains of the antenna elements and the diversity gain. It is proved that the proposed antenna can provide spatial and pattern diversity to combat multipath fading.     

太赫兹双频缝隙贴片天线的设计

提出了一种工作在太赫兹频段的双频缝隙贴片天线。在天线辐射贴片上加载“C”、“E”型辐射缝隙,改变天线表面电流的路径来实现双频特性。通过HFSS 15.0仿真软件对天线模型进行仿真,天线可以同时在300 GHz(291～306 GHz)和640 GHz(632～656 GHz)的频段下工作,最大增益达到了7.38 dB和10.50 dB。该双频天线结构简单,各项性能指标稳定,对于工作在太赫兹频段上的通信系统和无线传输系统具有一定的应用价值。     

一种高隔离度的双倒L形双频MIMO天线设计

研究了一种微带线馈电的双倒L形双频MIMO印刷天线结构,通过在倒L单极子结构上加载一条倒L形地板枝节,实现了天线的双频特性;通过在天线单元之间加载一条T形去耦枝节,有效提高了天线单元之间的隔离度。实验结果表明,天线在S11≤-10 dB时,工作频段分别为2.39~2.53 GHz和4.92~6.15 GHz,相对带宽分别为5.7%和22.2%,工作频段内隔离度均大于18 dB。此外,天线整体辐射特性较好,结构简单并易于制作,可应用于WLAN无线通信系统。