Ultra-thin single-layer transparent geometrical phase gradient metasurface and its application to high-gain circularly-polarized lens antenna

A new method to design an ultra-thin high-gain circularly-polarized antenna system with high efficiency is proposed based on the geometrical phase gradient metasurface(GPGM).With an accuracy control of the transmission phase and also the high transmission amplitude,the GPGM is capable of manipulating an electromagnetic wave arbitrarily.A focusing transmission lens working at Ku band is well optimized with the F /D of 0.32.A good focusing effect is demonstrated clearly by theoretical calculation and electromagnetic simulation.For further application,an ultra-thin single-layer transmissive lens antenna based on the proposed focusing metasurface operating at 13 GHz is implemented and launched by an original patch antenna from the perspective of high integration,simple structure,and low cost.Numerical and experimental results coincide well,indicating the advantages of the antenna system,such as a high gain of 17.6 d B,the axis ratio better than 2 d B,a high aperture efficiency of 41%,and also a simple fabrication process based on the convenient print circuit board technology.The good performance of the proposed antenna indicates promising applications in portable communication systems.     

High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface

Two substrate integrated waveguide (SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38% (4.05 GHz-5.95 GHz) and AR bandwidth of 24.9% (4.4 GHz-5.65 GHz). The bandwidth of the high gain antenna can reach 42.7% (3.95 GHz-6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.     

基于单层反射超表面的宽带圆极化高增益天线设计

基于Pancharatnam-Berry相位原理, 设计了一种宽带圆极化反射聚焦超表面并将其应用到提高天线增益中. 首先提出了一种变形十字超表面单元, 在11-16 GHz频带范围内能够实现高效同极化转换, 并基于该单元构建了宽带反射聚焦超表面. 仿真结果表明, 垂直入射的右旋圆极化平面波宽带聚焦效果明显. 然后利用单向阿基米德螺旋天线对超表面进行照射, 其辐射的球面波经超表面反射后得到了近平面波, 有效地提高了天线的增益. 最终对所设计的天线系统进行加工并测试, 结果表明系统的-1 dB增益带宽达到25% (12.5-16 GHz), 在该频带范围内峰值增益均高于19 dBc且轴比小于3 dB. 此外, 在12-15.5 GHz范围内天线口径效率均超过50%.     

一种基于开口谐振环的高增益端射天线设计

基于开口谐振环(split-ring resonator, SRR)奇异的电磁特性, 设计并制备了一种覆盖C和X波段的高增益SRR-Vivaldi端射天线. 采用等效分析方法对SRR结构谐振特性进行了研究, 并将其应用于传统Vivaldi天线指数渐变槽线前方, 使SRR结构形成特殊谐振能力的引向器, 将天线表面电流集中于端射方向, 在保证天线尺寸和带宽不变的前提下, 实现了天线增益的有效提升. 仿真和测试结果表明, 新型SRR-Vivaldi天线在C波段增益平均提高75.44%, xoy面和xoz面半功率波束宽度都缩减20°以上; 在X波段增益平均提高24.46%, xoz面半功率波束宽度大约缩减25°. 该结构具有低成本、设计简单、便于加工、利于共形等优点, 为端射天线提高增益和增强定向性提供了新思路.     

高功率双频宽谱平面倒F天线设计分析

设计了一种双频带的高功率宽谱平面倒F天线。在矩形贴片上开L形槽实现天线双频辐射。采用圆锥过渡实现同轴馈线到平板之间的宽带阻抗匹配;通过折叠振子电容加载和合理增加天线高度和宽度实现天线宽带设计。经过优化设计,实现了274 MHz和680 MHz的双频输出,反射系数S11不超过-6 dB的低频带宽和高频带宽分别达到14.6%和20.1%。天线的低频和高频增益分别达到4.4 dB和4.6 dB,对应辐射效率分别达到98%和99%。主辐射方向上的低频和高频远场辐射场与距离乘积与馈入宽带脉冲幅度比值分别为1.07和1.14。对天线的高功率容量进行了设计,将天线置于充0.2 MPa压力SF6气体的增强尼龙箱体中,天线可承受200 MW宽谱高功率微波。     

X波段高功率宽频带双螺旋反射阵列天线的设计

为了提升高功率微波辐射天线的带宽,提出并设计了一种X波段高功率圆极化反射阵列天线,该天线采用喇叭天线作为馈源,阵列天线单元由可旋转金属双螺旋线构成,通过旋转螺旋线可以实现360°的相位补偿,同时反射损耗极小。设计了15×15矩形栅格螺旋反射阵列天线,全波仿真结果表明：该口径为315 mm的阵列天线在中心频点9.3 GHz下,增益为28 dB,轴比为0.53 dB,口径效率为52.6%;在8.5~10.9 GHz的频带范围内增益大于26.8 dB,轴比小于1.14 dB,1 dB增益带宽和40%以上口径效率带宽均大于21%;在真空中所能承受的最大功率约为207 MW。     

Metamaterial-embedded dual wideband microstrip antenna for 2.4 GHz WLAN and 8.2 GHz ITU band applications

ABSTRACT

A compact dual-band antenna designed for operating in IEEE 802.11b/g WLAN (2.4–2.484?GHz) and ITU frequency bands (8.01–8.5?GHz) is presented in this communication. The antenna has two distinct resonant modes generated with the help of three U-shaped transmission lines and a modified ground plane. A periodic repeating pattern of metamaterial unit cells integrated on the same plane of the substrate has enhanced the antenna performances using improved loading method. The measured bandwidth of the metamaterial-embedded antenna is increased by 16% in the lower operating band and 6% in the upper operating band. The compact proposed antenna provides wide measured bandwidths of about 40% (2–3?GHz) in the lower and 16% (8.19–9.63?GHz) in the upper frequency spectra. The maximum measured gain of the proposed antenna is increased around 3.63?dB at 2.36?GHz and 1?dB at 8.45?GHz. The proposed antenna radiator is about 89.6% compact with respect to a conventional antenna. An excellent agreement of the simulation with the benchmark results validates the design of the proposed structure.     

A novel receiver-transmitter metasurface for a high-aperture-efficiency Fabry-Perot resonator antenna

This paper presents a novel coupled receiver-transmitter metasurface (MS) which is used to realize a high-aperture-efficiency Fabry-Perot resonator antenna. The unit cell of the MS adopts a slot-coupling procedure to realize energy transmission from the receiver patch to the radiator patch. This approach makes it easier to independently control the transmission magnitude and phase. Based on this characteristic, the transmission coefficients of different unit cells on the MS can be optimized by a genetic algorithm. Then, nearly uniform electric amplitude and phase distribution across the aperture field of the antenna are achieved. Therefore, the gain and aperture efficiency of the antenna are improved. A prototype of the optimized antenna is fabricated and measured to validate the design. The measured gain of the fabricated antenna reaches 17.3 dBi with an aperture efficiency of 94.5%. A higher aperture efficiency is obtained with the proposed antenna which has a low profile and simple structure.     

超薄宽带平面聚焦超表面及其在高增益天线中的应用

针对相位梯度超表面在灵活操控电磁波与提高天线增益中的潜在应用,提出一种新型的宽带超表面单元,实现了在较宽频带范围内操控电磁波波前与提高天线增益.本文首先设计了一种圆环十字形对称单元来控制反射波的相移量,单元厚度为1 mm,尺寸为0.3λ_0(λ_0=20 mm),工作频段15—18 GHz,而后验证了由该单元组成的相位梯度超表面在15—18 GHz范围内对电磁波的奇异反射与聚焦特性.最后将设计的反射聚焦超表面应用于提高天线增益中,仿真与测试结果均表明,天线最高增益在15—18 GHz内平均增加了11 d B且-1 dB增益带宽为15—18 GHz(相对带宽为18.2%).由于厚度薄、重量轻、频带宽,设计的该单元拓展了相位梯度超表面在微波领域的应用,有望为高增益天线的实现提供新的方法.     

Real-time programmable coding metasurface antenna for multibeam switching and scanning

Novel electromagnetic wave modulation by programmable dynamic metasurface promotes the device design freedom, while multibeam antennas have sparked tremendous interest in wireless communications. A programmable coding antenna based on active metasurface elements (AMSEs) is proposed in this study, allowing scanning and state switching of multiple beams in real time. To obtain the planar array phase distribution in quick response, the aperture field superposition and discretization procedures are investigated. Without the need for a massive algorithm or elaborate design, this electronically controlled antenna with integrated radiation and phase-shift functions can flexibly manipulate the scattering state of multiple beams under field-programmable gate array (FPGA) control. Simulation and experimental results show that the multiple directional beams dynamically generated in the metasurface upper half space have good radiation performance, with the main lobe directions closely matching the predesigned angles. This metasurface antenna has great potential for future applications in multitarget radar, satellite navigation, and reconfigurable intelligent metasurfaces.     

异面带状线馈电的宽带双极化蝶形天线

针对通信与雷达系统对双极化与宽带天线的要求,提出了一种基于带状线馈电的双极化蝶形天线。通过两对互相正交的蝶形阵子实现了天线的双极化,并采用一种新型的微带线转异面带状线的巴伦给两对正交蝶形阵子平衡馈电。异面带状线为平衡传输线,满足了蝶形阵子对于平衡馈电的要求。在馈电点处由同轴线对微带线馈电,经渐变微带线转化为异面带状线,最后由两组异面带状线给两对正交蝶形阵子馈电。测得该天线实现了69.23%的阻抗带宽,在6.8~14GHz频带内电压驻波比(VSWR)小于2。为使天线单向辐射且改善天线增益,将天线放置于反射吸收腔内。测得天线在6.8~18GHz的频宽内VSWR基本小于3,天线增益在8~12GHz频带内大于0.11dB,天线前后瓣比大于15dB。因此,所提出的双极化蝶形天线可用于宽带通信系统中。     

基于极化旋转超表面的圆极化天线设计

本文通过设计出一种反射型极化旋转超表面,在8—12 GHz频域内实现高效的极化旋转,并将其加载于微带缝隙天线下方构成新型的极化旋转超表面天线,利用超表面的90°极化旋转效应,成功实现了天线的圆极化辐射调制.仿真与实验结果表明:圆极化天线的中心工作频率为GHz,阻抗带宽为8.3—10 GHz.当微带缝隙天线与极化旋转超表面的间距H=4.5mm时,天线在8.3—8.8 GHz频带内实现了圆极化辐射;当mm时,天线在8.8—9.3 GHz频带内实现了圆极化辐射;当=8mm时,天线在9.3—10 GHz频带内实现了圆极化辐射.实验结果与仿真结果相符,证明了此种设计方法的有效性,也为微带缝隙天线的圆极化设计提供了一种新的途径.     

异面带状线馈电的宽带双极化蝶形天线

针对通信与雷达系统对双极化与宽带天线的要求,提出了一种基于带状线馈电的双极化蝶形天线。通过两对互相正交的蝶形阵子实现了天线的双极化,并采用一种新型的微带线转异面带状线的巴伦给两对正交蝶形阵子平衡馈电。异面带状线为平衡传输线,满足了蝶形阵子对于平衡馈电的要求。在馈电点处由同轴线对微带线馈电,经渐变微带线转化为异面带状线,最后由两组异面带状线给两对正交蝶形阵子馈电。测得该天线实现了69.23%的阻抗带宽,在6.8～14 GHz频带内电压驻波比(VSWR)小于2。为使天线单向辐射且改善天线增益,将天线放置于反射吸收腔内。测得天线在6.8～18 GHz的频宽内VSWR基本小于3,天线增益在8～12 GHz频带内大于0.11 dB,天线前后瓣比大于15 dB。因此,所提出的双极化蝶形天线可用于宽带通信系统中。     

Shared aperture metasurface antenna for electromagnetic vortices generation with different topological charges

Vortex beams carrying orbital angular momentum (OAM) have aroused great interest of both scientific and engineering communities. Encouragingly, generating OAM with different topological charges in a shared aperture is regarded as a potential route to expanding the communication capacity, which yet is an academic challenging task. In this work, a paradigm of designing metasurface-based shared aperture antenna for generating polarization-dependent vortex beams with distinct topological charges is proposed. Anisotropic unit cells that can tailor different resonance phase profiles in two orthogonal orientations are used to assemble a metasurface reflector. As a proof-of-concept, a planar reflector antenna is designed with two Vivaldi sources, which can generate x- and y-polarized vortex beams with topological charges of l=-1 and l=-2, respectively. Both the simulation results and the measurement results are in good agreement, which demonstrates the feasibility of our design. Significantly, this work provides a new route to achieving vortex beams carrying different topological charges in the same frequency band, which may have potential applications in communication systems.     

超宽带异向介质平面倒F天线

将异向介质地板引入平面倒F天线（PIFA）的设计中,探索了这种天线的新型辐射特性.修正的PIFA传输线模型中,利用异向介质的谐振电路取代了传统辐射贴片不连续性而引起的电容效应,从物理上有效地解释了这种PIFA辐射性能的提高.数值和实测数据表明,该PIFA天线-10 dB相对带宽超过了100%,谐振频率包含无线局域网络各通信标准及城域网2—6 GHz固定和移动宽带无线接入系统的所有载波频段.在2.4/2.5 GHz时,该天线将得到全向的辐射方向图,而在3.8 GHz和5.1—5.8 GHz频带内,该天线更集 关键词： 异向介质 传输线模型 平面倒F天线 超宽带     

同轴线直馈的T2模四臂螺旋全向圆极化天线

基于T2模四臂螺旋,提出一种新型的全向圆极化天线。T2模全向圆极化天线无需采用复杂的馈电网络,而采用同轴线直接馈电,即同轴电缆的内、外导体依次交替馈电至天线的四个螺旋臂,巧妙实现了T2模四臂螺旋的馈电相位要求(0-180-0-180);为了提高天线的辐射效率,螺旋线采用线宽捷变技术（即螺旋臂的前面部分窄、后面部分宽）;为了保持天线的圆极化特性,螺旋线末端加载吸收导线。对天线进行了仿真和测试,两者结果吻合好,天线的实测增益为10.5 dBi、轴比为1.3 dB,水平圆度为2.3 dB。     

电-磁振子组合型宽带高功率微波辐射天线仿真与设计

为了满足宽带高功率微波辐射系统紧凑化的需求,设计了一个口径面尺寸为20 cm20 cm的电-磁振子组合型天线,采用三维全波电磁场仿真,得到该天线在0.3~1.7 GHz 带宽内的驻波比小于3,且在此带宽内天线增益均大于2。仿真分析了该天线结构的尺寸、电流环长度以及天线开口角度对电-磁振子组合型天线阻抗带宽和增益的影响。在此基础上,给天线馈入峰值为226 kV的宽带信号,仿真得到天线的最大辐射因子为150 kV,等效峰值功率为358.8 MW,辐射效率约70.6%。仿真结果表明：组合振子天线能够满足宽带高功率微波的辐射要求,同时满足辐射系统紧凑化和高辐射效率的要求。     

二维宽带相位梯度超表面设计及实验验证

针对圆极化波, 通过同极化反射超表面结构单元的空间排布, 设计实现了一种二维非色散高效相位梯度超表面. 同极化反射相位可以通过同极化反射超表面结构单元金属线的面内旋转来自由调控. 实现的相位梯度超表面可对左右旋入射波产生相反的相位梯度. 当线极化波入射到超表面上时, 反射波被分为两束向相反方向传播的圆极化波. 仿真了线极化波垂直入射时的反射功率密度谱, 仿真结果与理论上设计的异常反射方向一致. 制作了厚度为2 mm的超表面样品, 测试了其镜面反射率曲线. 实验结果表明, 线极化波垂直入射时, 超表面在9.5-19.0 GHz的镜面反射率降至-5 dB以下.     

高增益宽带圆极化Vivaldi天线阵的设计

提出了一种由新型Vivaldi天线单元构成的22十字交叉圆极化天线阵。Vivaldi天线单元采用边缘渐变对拓的锯齿结构,提高了天线在4.7～7.0 GHz频带内的增益,其反射系数低于-10 dB的带宽为2.4～11.0 GHz,具有超宽带线极化特性。圆极化天线阵测量结果显示,在4.5～7.0 GHz频带范围内,其轴比均低于3 dB,且整个频带范围内增益达11～13 dBi。     

一种兼有高增益和宽带低散射特征的波导缝隙天线设计

设计了一种同时具备高增益和宽带低散射特征的波导缝隙天线.将蚀刻有互补开口谐振环的方形贴片人工磁导体正交布阵得到宽带低雷达截面积(RCS)反射屏并以之代替原天线的全金属反射板,通过优化反射屏的加载方式,在展宽天线工作频带、提高天线增益的同时,实现了宽频域范围内天线鼻锥方向RCS减缩.实测结果表明:加载低RCS反射屏的缝隙天线工作带宽增加了100 MHz,前向增益提高了3.2 dB,在5.52—6.63GHz范围内RCS减缩量达10 dB以上,减缩带宽达到20%.