A circularly polarized slot antenna for high gain applications

A coplanar waveguide fed slot antenna for wideband circular polarization is designed and experimentally validated. The rectangular slot is excited using a stepped feed line terminated on a circular disc shaped tuning stub. To obtain circular polarization, inverted L-shaped strips are attached to the ground plane at the opposite corners while a rectangular slit is cut in the circular disc. The combined bandwidth (3-dB axial ratio and 10 dB impedance matching) achieved is 48% (4.35–7.1 GHz) under simulation and 40% (4.75–7.1 GHz) in measurement. The gain of the antenna is next enhanced by the application of a double layered square loop frequency selective surface. The frequency selective surface is used as a reflector placed beneath the antenna at an optimum distance. An improvement of about 4 dB is seen in the measured peak gain over most of the operating band. Experimental results are presented to characterize the antenna and the frequency selective surface and they are found to be in good agreement with the simulated results.     

基于开口谐振环的微带天线互耦抑制研究

提出了一种通过加载开口谐振环隔离板来抑制微带天线阵元之间耦合的方法。首先设计了一款工作频率在6GHz的微带天线阵,然后在其阵列单元间加载单环SRR隔离板结构。该结构在特定频段具有带阻特性,可以有效抑制天线单元间的互耦,增加天线单元间的隔离度。最后利用HFSS软件进行了仿真与优化。仿真结果证明:该结构的引入能使微带天线单元间的互耦因子降低10d B左右,体现了较好的互耦抑制特性。     

基于超材料的宽带高增益低雷达散射截面天线

利用超材料概念,通过在天线贴片和接地面上分别蚀刻周期互补三角形电磁谐振单元(CTER)和条形缝隙图案,在低介电常数薄介质基板上设计并且制作了一种宽带高增益低雷达散射界面(RCS)贴片天线。仿真分析表明:由于超材料结构的左手特性影响了天线介质基底的等效媒质参数,天线电磁场的传播方向被改变,天线辐射场主要集中在水平方向而不是传统贴片天线的垂直方向。相比初始天线,新天线相对带宽从2.9%扩展到64.5%,并且有低的电压驻波比;在工作带宽内,天线鼻锥方向低雷达散射界面都有5dB以上的减缩,最大减缩22dB.实验结果与仿真结果有较好的一致性。     

高温超导天线在天线RCS减缩中的应用

高温超导(HTS)体由于具有较低的表面电阻,在天线应用中,它可以提高天线的效率.天线作为特殊的散射体,会将部分接收的入射场再辐射出去,而超导天线散射场的强度可以通过控制温度来进行控制,并且高温超导微带天线可以实现天线小型化,这就可以实现减缩天线雷达散射截面(RCS)的目的.对高温超导线天线和微带贴片天线的分析结果证明了结论的可行性.这是超导体除了增加天线效率以外的在天线设计方面的另一个应用.     

Metamaterial inspired quad band circularly polarized antenna for WLAN/ISM/Bluetooth/WiMAX and satellite communication applications

A CPW fed metamaterial inspired Quadband circularly polarized antenna is presented in this article. The proposed antenna consists of defected ground structure with a radiating stub, which is at opposite side of the feedline. A waveguide mode of analysis is carried out for split ring resonator (SRR) and complimentary split ring resonator (CSRR) to enhance the properties of metamaterials. The proposed antenna analysis is taken iteration wise and used FR-4 Material as the substrate material with Ɛ_r = 4.4 and analysed using ANSYS electromagnetic desktop. The designed antenna projecting the peak gain of 4.8 dB and it is working in the application bands of WLAN/ISM/Bluetooth at 2.4 GHz, 5.8 GHz and 3.35 WiMAX band, X-band downlink satellite communication system (7.25–7.75 GHz) and ITU band (8–8.5 GHz) with fractional bandwidth of about 70%. Proposed antenna exhibits circular polarization at 2.39–2.55 GHz, 3.05–3.1 GHz, 4–5 GHz and 6.3–6.64 GHz respectively. To know the signal integrity of the antenna, time domain analysis is carried out for identical antennas in two conditions (face to face and side by side) with the help of CST microwave studio. The designed antenna showing excellent correlation in measurements with respect to simulation results.     

圆极化径向线缝隙天线的研究

讨论了圆极化向线缝隙天线的几何结构,口径场分布、缝隙对设计。在此基础上,讨论了慢波结构和波导结构关系,分析了慢波结构对天线的影响,完成了该天线的计算机辅助设计和绘图,使用该方法给天线设计带来了方便,能灵活地调整缝隙排列、优化排列结构,具有直观和精度高的优点。     

Circularly polarized co-designed filtering annular slot antenna

In this paper, a compact circularly polarized co-designed filtering annular slot antenna (ASA) is proposed. The antenna comprises a distributed capacitor-loaded annular slot radiator to produce circular polarization (CP) radiation, which is seamlessly integrated with a microstripline bandpass filter (BPF) to enhance out-of-CP-band suppression. Two tightly coupled arc branches protruding into the annular slot are used to provide the required perturbation capacitance. The filter is designed by employing three concentric arc-shaped coupled microstripline resonators. The ground plane is shared by the annular slot radiator and the filter to reduce size occupation. It is found that the proposed antenna can not only yield high frequency selectivity, but also obtain widened CP bandwidth under the assistance of the filtering circuit. An antenna prototype has been fabricated and measured, showing that the antenna achieves a 10 dB return loss impedance bandwidth of around 13.7%, enclosing a 3 dB axial ratio (AR) bandwidth of more than 10.6%. Details of design considerations and experimental results are presented and discussed.     

低RCS栅格微带天线研究

研究了栅格微带天线在微带天线RCS减缩中的应用。分析了栅格线宽度、栅格线间距、栅格化方式等参数对天线的谐振频率、增益的影响。设计了一副具有低RCS特性的栅格微带天线,与谐振在同频率的微带贴片天线相比,天线的增益仅降低0. 6dBi,而天线在2~10GHz频带内的平均RCS降低4dBsm。     

Penta-notched UWB antenna with sharp frequency edge selectivity using combination of SRR,CSRR, and DGS

This work presents penta-notched UWB antenna with sharp frequency edge selectivity using combination of SRR, CSRR, and DGS to reject the WiMAX (3.30–3.60 GHz), lower WLAN (5.150–5.350 GHz), upper WLAN (5.725–5.825 GHz), downlink of X-band satellite communication (7.0–7.40 GHz), and the uplink of X-band satellite communication (8.10–8.50 GHz) frequency bands. All these frequency bands lie within the UWB frequency spectrum. The proposed antenna is suitable for portable communication applications due to its compact dimensions. It sharply notches the existing frequency bands to mitigate the interference caused by nearby wireless communication systems within UWB frequency range. The sharp notching is achieved by the combination of complementary split ring resonators (CSRR) on the radiating semi-circular patch, split ring resonators (SRR) placed at the junction of the feedline, and a pair of defected ground structures (DGS). All notched bands can be well controlled and shifted and the equivalent lumped model of the notched bands are also developed for validation. The proposed antenna simulated, and measured results show better performance over the present state-of-the-art designs. The proposed penta-notched UWB antenna possesses better reflection coefficient, VSWR, stable gain, and small foot print. The proposed antenna has a nearly omnidirectional radiation pattern in the passbands.     

基于人工磁导体的低RCS微带天线设计

基于人工磁导体(AMC)的工作机理,设计了一款工作频率在X波段的低雷达散射截面(RCS)微带天线。设计了一种AMC单元,经X和Y极化波垂直入射在8.6~14.6 GHz的频带范围内,获得180°±37°的反射相位差;将其进行正交排列组成AMC棋盘结构的反射屏,反射屏中AMC阵列块由3×3的单元组成。仿真结果显示,该反射屏较相同尺寸的PEC板具有更小的后向RCS,将此AMC结构与工作频点为10 GHz的微带天线共面排布,在保持原有天线良好辐射性能和剖面高度的同时,在8.4~14.8 GHz的频率范围内对两种极化波垂直入射实现了不低于7.5 dB的RCS缩减量。     

基于二维微波成像的共形天线RCS提取方法

二维微波成像技术是一种有效诊断雷达目标散射点强度和空间分布的手段。机载共形天线因与机体表面成为一体,常规测试手段难以确定其RCS贡献。基于二维微波成像技术,分离和提取出了装机状态下共形天线的反射率分布,通过二维空间像与二维空间谱之间的波谱变换获得了共形天线的二维空间谱信息,经过直角坐标域至极坐标域的插值获得了对应频率和角度的散射信息,再对定标球进行同样的处理,最终标定出共形天线的RCS贡献。实验结果表明了该技术的有效性。     

实用型等离子体天线的研制与测试

为了解决等离子天线增益低、噪声大、体积大、质量重、功耗高等问题.在天线增益取得突破性进展的基础上,通过重新设计天线激励源和各主要腔体等措施,研制了一款新型等离子体天线样机,该样机尺寸小、质量轻,并实现了低噪声和较低的功耗.在外场测试中,该样机达到与金属天线相近的增益水平.     

圆极化微带贴片天线辐射和散射特性研究

提出了一种改进的宽带圆极化微带天线。该天线采用单端口、共面波导馈电。通过仿真优化,获得了32.7%的圆极化轴比带宽(AR<3dB),和47.6%的阻抗带宽(VSWR<2.0)。测量天线样机的阻抗带宽为44.4%,较好地吻合了仿真计算结果。最后,以设计天线为例,研究了圆极化微带贴片天线的辐射特性和散射特性,为圆极化天线雷达截面减缩技术打下了良好的理论和实验基础。     

隐身飞行目标低频段RCS计算

本文在采用计算机图形学对某犁隐身飞机进行电磁建模的基础上,利用FDTD方法和电磁计算软件Microwave Studio对飞机在低频段(短波和米波波段)的RCS进行了计算,包括不同极化和不同入射角度条件下的单站和双站RCS.比较两种方法的计算结果证明在低频段该飞机有可能出现较强的谐振频率点,因而利用低频段雷达有可能实现对隐身飞机等低可探测目标的检测和跟踪.     

Design of a Vivaldi antenna with wideband reduced radar cross section

In this paper, a low radar cross section (RCS) Vivaldi antenna is proposed. The main objective of this work is to achieve a reasonable RCS reduction without affecting the radiation performance of the antenna. With carefully inspecting the surface current distributions at different frequencies and realizing the critical role of the structural mode in reducing RCS, a simple and efficient object shaping method is employed by introducing a number of circular slots in the surface of the radiator to achieve the RCS reduction. These circular slots along the inner circular profile of the Vivaldi antenna can minimize the scattering along the surface of the radiator, which hence leads to a reduction in the monostatic RCS. Comparing the measured results between the reference antenna and the proposed antenna, a significant 11 dB RCS reduction is obtained while maintaining good radiation performance. Simulated and measured results including S-parameters, gain, RCS of the reference antenna and the proposed antenna are presented.     

超电大复杂目标RCS缩比模型预估方法

本文提出用缩比模型计算电大目标雷达散射截面（RCS）的理论。通过复杂目标近远场电磁散射理论模型的分析得到，目标的雷达截面和目标的几何尺寸及工作波长有关系。当电尺寸相同时，目标雷达散射截面和其几何尺寸的平方成正比，缩比模型计算既适用于近场，也适用于远场。     

A novel wideband and circularly polarized cross‐dipole antenna

In this paper, we present a novel wideband circularly polarized (CP) composite, called cavity‐backed crossed dipole antenna for 2.45 GHz industrial, scientific, and medical (ISM) band wireless communication. To excite the CP radiation effectively, a curved‐delay line providing an orthogonal phase difference among the cross‐dipole elements is attached at corners of the sequentially rotated elements. By choosing a proper radius of the curved‐delay line, a wide input impedance of the antenna can be realized. Unlike conventional cross‐dipole antennas, the proposed cross‐dipole antenna is designed with an open stub added to the radiating arms of the dipole so that both impedance and axial ratio bandwidths are enhanced. The antenna is center‐fed by a 50‐Ω coaxial cable and is placed above a cavity‐backed reflector to obtain a directional CP radiation pattern. With the advantage of being center‐fed, a symmetric CP radiation pattern can be achieved across the entire operating bandwidth. To further improve the directivity and the radiation pattern, a rectangular cavity‐backed reflector is used. Simulated and measured results confirm that the proposed antenna has good CP characteristics. The proposed antenna obtains a broad 3‐dB axial ratio bandwidth of 49% (1.20 GHz, 1.96–3.16 GHz) and an impedance bandwidth of 67.7% (1.66 GHz, 1.69–3.35 GHz) for reflection coefficient (S₁₁) ≦ −10 dB. It also yields an average CP gain of 9.2 dBic across the operating bandwidth and a peak CP gain of 10 dBic. Copyright © 2016 John Wiley & Sons, Ltd.     

基于LabVIEW的标签差分雷达截面分析与测量

差分雷达截面(ARCS)是描述无源超高频射频识别(UHF RFID)标签性能的重要参数,它决定标签到阅读器的反向链路误码率.但是,没有直接测量ARCS的方法,需要采取间接方式进行测量.基于NI的射频板卡,开发了标签反射矢量信号分析软件,给出△RCS的测量方法,并对贴附物材料及发送功率对ARCS的影响进行了分析和测量.     

新型超宽带微带天线辐射和散射特性研究

提出了一种改进的超宽带微带贴片天线。天线以共面波导方式馈电,其阻抗带宽在满足VSWR<2.0条件下的仿真计算结果为2.5~20 GHz,天线样机实测结果为2.8~18.7 GHz。研究天线的辐射和散射特性,并与参考天线作对比,发现在同样满足超宽带宽的条件下,设计的天线具有良好的RCS减缩效果。以设计天线为例,分析了超宽带微带天线的散射特性,为超宽带天线雷达截面减缩技术打下了良好的理论和实验基础。