An externally perceivable smart leaky-wave antenna based on spoof surface plasmon polaritons

Smart antennas have received great attention for their potentials to enable communication and perception functions at the same time.However,realizing the function synthesis remains an open challenge,and most existing system solutions are limited to narrow operating bands and high complexity and cost.Here,we propose an externally perceivable leakywave antenna(LWA)based on spoof surface plasmon polaritons(SSPPs),which can realize adaptive real-time switching between the“radiating”and“non-radiating”states and beam tracking at different frequencies.With the assistance of computer vision,the smart SSPP-LWA is able to detect the external target user or jammer,and intelligently track the target by self-adjusting the operating frequency.The proposed scheme helps to reduce the power consumption through dynamically controlling the radiating state of the antenna,and improve spectrum utilization and avoid spectrum conflicts through intelligently deciding the radiating frequency.On the other hand,it is also helpful for the physical layer communication security through switching the antenna working state according to the presence of the target and target beam tracking in real time.In addition,the proposed smart antenna can be generalized to other metamaterial systems and could be a candidate for synaesthesia integration in future smart antenna systems.

Spoof surface plasmon-based bandpass filter with extremely wide upper stopband

We investigate the guiding modes of spoof surface plasmon polaritons （SPPs） on a symmetric ultra-thin plasmonic structure. From the analysis, we deduce the operating frequency region of the single-mode propagation. Based on this property, a spoof SPPs lowpass filter is then constituted in the microwave frequency. By introducing a transmission zero at the lower frequency band using a pair of stepped-impedance stubs, a wide passband filter is further realized. The proposed filter is fed by.a transducer composed of a microstrip line with a flaring ground. The simulated results show that the presented filter has an extremely wide upper stopband in addition to excellent passband filtering characteristics such as low loss, wide band, and high square ratio. A prototype passband filter is also fabricated to validate the predicted performances. The proposed spoof-SPPs filter is believed to be very promising for other surface waveguide components in microwave and terahertz bands.

Spoof surface plasmon polaritons excited leaky-wave antenna with continuous scanning range from endfire to forward

A novel leaky-wave antenna(LWA)utilizing spoof surface plasmon polaritons(SSPPs)excitation is proposed with continuous scanning range from endfire to forward.The designed transmission line unit supports two SSPPS modes,of which the 2nd order mode is applied in the design.A novel strategy has been devised to excite the spatial radiation of the-1st order harmonics by arranging periodic counter changed sinusoidal structures on both sides of the SSPPs transmission line.Both full-wave simulation and measurement results show that the proposed LWA presents wide scanning angle from endfire to forward.In the frequency range from 4 GHz to 10 GHz,LWAs achieve scanning from 90°to+20°,covering the entire backward quadrant continuously.

Anomalous microwave reflection from a metal surface induced by spoof surface plasmon

The reflection of X-band microwaves （8-12 GHz） from a metallic aluminum （A1） surface with groove grating corrugations was investigated experimentally. It was shown that the reflection of p-polarization is much less than the microwave reflected from the corresponding area of an unruled Al surface, with selective wavelength. The experimental results demonstrated that the anomalous microwave reflection is strongly associated with the excitation of spoof surface plasmons at the Al air interface by the surface grating coupler. This near-total absence of reflected microwaves is similar to the famous Wood＇s anomaly in the optical regime and is of fundamental importance to the applications of spoof surface plasmons in the microwave regime.

High-confinement ultra-wideband bandpass filter using compact folded slotline spoof surface plasmon polaritons

A novel bandpass filter(BPF)based on spoof surface plasmon polaritons(SSPPs)using a compact folded slotline structure is proposed and experimentally demonstrated.The proposed novel SSPPs structure compared with a conventional plasmonic waveguide with slot line SSPPs unit structure at the same size,the considerable advantages in much lower asymptotic frequency with tight field confinement,which enable the proposed filter to be more miniaturization.A high-efficient mode conversion structure is designed to transition from TE-mode to SSPPs-mode by gradient slotline lengths.The low-frequency stop-band can be committed with microstrip to slotline evolution on both sides of the dielectric,while the high-frequency cutoff band is realized by the proposed SSPPs structure.The influence of dispersion relation,electric field distribution,surface current,and structural parameters on the transmission characteristics of the proposed BPF are analyzed by finite difference time domain(FDTD).To validate the design concept,the prototype of the miniaturized SSPPs BPF has been manufactured and measured.The experimental results show high performance of the fabricated sample,in which the working in a range of 0.9 GHz-5.2 GHz with the relative bandwidth is 142%,the insertion loss less than 0.5 dB,the reflection coefficient less than-10 dB,and the group delay is less than one ns.This works provides a mirror for realizing the miniaturization of waveguides,and the application and development of high-confinement SSPPs functional devices in the microwave and THz regimes.

Single-beam leaky-wave antenna with wide scanning angle and high scanning rate based on spoof surface plasmon polariton

We propose a single-beam leaky-wave antenna(LWA) with a wide-scanning angle and a high-scanning rate based on spoof surface plasmon polariton(SSPP) in this paper. The SSPP transmission line(TL) is etched with periodically arranged circular patches, which converts the slow-wave mode into the fast-wave region for radiation. The proposed LWA is designed, fabricated, and tested. The simulated results imply that the proposed LWA not only achieves a high radiation efficiency of about 81.4%, and a high scanning rate of 12.12, but also has a large scanning angle of 176° over a narrow operation bandwidth of 8.3-9.6 GHz(for |S_(11)| <-10 dB). In addition, the simulated average gain of the LWA can reach as high as 10.9 d Bi. The measured scanning angle range is 175° in the operation band of 8.2-9.6 GHz, and the measured average gain is 10.6 dBi. The experimental results are consistent with the simulation, validating its performance. An antenna with high radiation efficiency, wide scanning angle range, and high scanning rate has great potential for application in radar and wireless communication systems.

A Cogwheel WGM Resonator Based on Spoof Surface Plasmon Polaritons

The optical WGM resonator plays an important role in modern physics due to its ultra-high quality factor and small volume mode. In optics, SPPs modes can effectively confine electromagnetic waves at the interface between metal and dielectric, providing extremely high sensitivity. New interesting WGM phenomena will emerge when the WGM is combined with the SPPs. In this paper, a cogwheel resonator based on spoof SPPs was designed, which can generate multi-order WGM modes. The transmission coefficients, dispersion relations and resonance modes of the WGM resonator were analyzed. The proposed resonator extends the WGM mode from optical band to microwave band, providing a new perspective for the applications of WGM mode at microwave band.

Polarization-insensitive unidirectional spoof surface plasmon polaritons coupling by gradient metasurface

A polarization-insensitive unidirectional spoof surface plasmon polariton（SPP） coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs are analyzed. The simulated and experimental results support the theoretical analysis and indicate that the designed gradient metasurface can couple both the parallel-polarized and normally-polarized incident waves to the spoof SPPs propagating in the same direction at about 5 GHz.

基于SSPPs传感器的金属凹槽填充工件检测

提出了一种基于液体开关控制的人工表面等离激元传感器,用于检测金属凹槽填充密度。该传感器由液体开关控制器和功分结构组成。液体开关由塑料管和带水的注射器组成,固定在SSPPs传感器的分支结构上。塑料管内充满水时,支路不能传输信号,这称为“OFF”状态。相反,塑料管内无水时称为“ON”状态。通过切换传感器支路的“ON”或“OFF”状态,可以控制SSPPs传感器的传感区域。该检测方法是基于凹槽填充质量变化引起的SSPPs传感器反射系数的变化,通过切换支路状态,可以检测各支路下方是否存在填充质量问题。实验结果表明,SSPPs传感器可以有效检测10 mg填充变化,可用于实现批量生产工件的快速筛选。

Reconfigurable exceptional point-based sensing with 0.001λsensitivity using spoof localized surface plasmons

Recent breakthroughs in the field of non-Hermitian physics present unprecedented opportunities,from fundamental theories to cutting-edge applications such as multimode lasers,unconventional wave transport,and high-performance sensors.The exceptional point,a spectral singularity widely existing in non-Hermitian systems,provides an indispensable route to enhance the sensitivity of optical detection.However,the exceptional point of the forementioned systems is set once the system is built or fabricated,and machining errors make it hard to reach such a state precisely.To this end,we develop a highly tunable and reconfigurable exceptional point system,i.e.,a single spoof plasmonic resonator suspended above a substrate and coupled with two freestanding Rayleigh scatterers.Our design offers great flexibility to control exceptional point states,enabling us to dynamically reconfigure the exceptional point formed by various multipolar modes across a broadband frequency range.Specifically,we experimentally implement five distinct exceptional points by precisely manipulating the positions of two movable Rayleigh scatterers.In addition,the enhanced perturbation strength offers remarkable sensitivity enhancement for detecting deep-subwavelength particles with the minimum dimension down to 0.001λ(withλto be the free-space wavelength).

基于SSPPs的低剖面宽带八木天线阵列设计

提出了一种基于新型人工表面等离子体激元(Spoof Surface Plasmon Polaritons,SSPPs)馈电带有引向器的低剖面宽带八木天线阵列。天线阵列包括两部分:基于人工表面等离子体激元波导的四路宽带功分器和八木天线阵列。人工表面等离子体激元具有高的场局限性,将信号束缚在人工表面等离子体激元的凹槽结构中保证了信号的高效传输,减少了传输损耗。八木天线通过进一步加载引向器结构能够实现端射辐射特性。测试结果表明:天线阵列的回波损耗在4.5~6.05 GHz频率范围内小于-10 dB。天线阵列实际增益在4.5~6.05 GHz范围内最高可达11.1 dBi。

基于SSPP技术的家庭网络多波束天线技术研究及应用

大带宽、广覆盖、低时延和抗干扰的高品质家庭无线网络是保障光纤入房(FTTR,fiber to the room)千兆光网用户体验的关键指标,传统家庭网络设备主要采用单波束单极化天线设计,在大衰减、强干扰背景下已经越来越无法满足高品质的网络产品需求。天线作为实现传导能量与空口电磁波变换必不可少的部件,利用其设计自由度可以实现多重功能。高增益能降低射频端的功耗需求,达到节能的目的,多波束能保持无死角的高性能网络覆盖,因此研究设计小尺寸、高增益且用法灵活的多波束天线价值巨大。紧跟实际工程痛点和当前学术研究方向,瞄准家庭网络产品设计开发了一种基于人工表面等离激元(SSPP,spoof surface plasmon polariton)技术的家庭网络多波束天线,覆盖Wi-Fi的5.1~5.9 GHz频段。实际测试验证表明,基于SSPP技术的天线设计能够获得更好的覆盖性能,相比传统小天线,在穿墙、跨层等弱信号场景下具有明显优势,在小型化的家庭网络产品中具有极大的应用前景。

混合基片集成波导的SSPPs带通滤波器设计与实现

人工表面等离子体激元(SSPPs)具有低损耗、高束缚、传输效率高的优点,易于平面集成,并被广泛应用于微波滤波器电路设计。文中在具有高通特性的基片集成波导(SIW)上表面刻蚀具有低通特性的SSPPs结构,将二者有机结合设计出一款混合基片集成波导带通滤波器。仿真结果表明,该滤波器在13 GHz^17 GHz的通带内回波损耗均在-11 dB以下,插入损耗在-1.2 dB左右,在截止频率以外较宽的频带内具有优于-80 dB的优越带外抑制;测试结果和仿真结果高度一致,其回波损耗优于-15 dB,插入损耗在-4 dB左右;通过对平坦和弯曲情况下的滤波器进行对比测试,发现两种状态下的测试高度吻合,证明混合SIW的SSPPs带通滤波器优异的微波特性,并为其在柔性电路的应用提供了研究依据。

Negative-index dispersion and accidental mode degeneracy in an asymmetric spoof-insulator-spoof waveguide

It has been recently demonstrated that negative-index dispersion and mode degeneracy can be achieved by manipulating a spoof-insulator-spoof（SIS） waveguide. In this paper, we propose a new SIS waveguide, which is composed of two spoof surface plasmon polaritons（SSPPs） waveguides drilled with periodic rhomboidal grooves. Both the symmetric and asymmetric cases are investigated. Our simulation results show that the asymmetric SIS waveguides are more significant.By tailoring the tilt of the rhomboidal grooves, the negative-index dispersion can be achieved and the microwave band gap（MBG） can be effectively modulated. At a critical tilt, there appears an accidental mode degeneracy at the edge of the first Brillouin zone. The excitation and propagation of the two coupled modes sustained by the asymmetric SIS waveguides are also demonstrated.

柔性电磁超构表面的太赫兹等离子体诱导透明效应

介绍了上海师范大学光学学科团队太赫兹(THz)微纳结构光子学课题组的主要成果:通过改变电磁谐振单元空间对称性,实现不同类型的等离子体诱导透明(PIT)现象,从而实现对太赫兹电磁脉冲群延迟的调控,获得太赫兹波段的慢光效应,同时衍生出了一系列全新的太赫兹光谱现象,拓展了人们对太赫兹PIT成因的认知.主要内容涵盖如下方面:非对称近场耦合实现宽频带慢光;导电耦合实现双暗场激发慢光;三体耦合局域化慢光;自互补结构单元实现正负相反的干涉相消共振,获得不同程度的太赫兹慢光;类表面等离子体相互作用获得慢光等.这些工作实现了太赫兹慢光调控机制的创新.

电磁超材料的发展与应用

电磁超材料也被称为新型人工电磁材料,是亚波长尺度单元按周期或非周期排列构成的人工结构,具有传统材料不存在或传统技术难以实现的超常规媒质参数,可对电磁波进行精细调控。超材料是材料、结构、功能的复合体,超越了传统材料的概念和范畴,并已遍布与“波”相关的领域,包括电磁、声学、力学、热学和量子等。近二十年来,电磁超材料一直是物理和信息领域的国际前沿研究热点,由此衍生的相关技术也在通信、雷达和成像等多个领域产生了具有颠覆性效应的一系列应用。

基于人工表面等离激元的小型化电可调缺口带滤波器

具有小型化的缺口带滤波器在微波集成系统中具有广泛的应用前景.本文基于倒山形单元的人工表面等离激元(spoof surface plasmon polariton,SSPP)提出了一种新型小型化电可调缺口带滤波器.与相同横向尺寸的传统SSPP单元相比,所提出的倒山形单元的色散曲线表现出更好的慢波特性,渐近频率降低至原来的55%.缺口带的频率可通过调整变容二极管两端的偏置电压来动态控制.随着偏置电压从0.5 V增至30 V,缺口带频率从2.1 GHz移动到2.3 GHz,实现动态调节.仿真结果表明,缺口带滤波器通带内实现了较低的插入损耗(S_(21)<-1 dB)和良好的回波损耗(S_(11)>-10 dB),并且具有小型化的优势,尺寸仅为0.78λ_(g)×0.35λ_(g),λ_(g)是中心频率处的波长.采用印刷电路板技术实际加工了缺口带滤波器.实物测量和仿真结果吻合较好,验证了设计的可靠性.

面向极端环境的石墨烯人工表面等离激元天线阵

面向极端环境中的通信与探测需求,提出一种石墨烯人工表面等离激元天线阵。该天线采用高导电石墨烯薄膜材料制成,结构形式为人工表面等离激元。其中,人工表面等离激元电磁结构分为传输段与辐射段,传输段用以实现显著的慢波特性与场局域性,进而获得低剖面与小型化;辐射段用以实现高定向性的端射辐射,并进行方向图合成。高导电石墨烯薄膜使天线拥有多种物化环境下的耐受性。经仿真与实测验证,天线整体剖面为50μm,在1000次弯折试验、-200~200℃高低温试验、酸性试验、碱性试验、盐雾试验的极端条件试验后,能够提供5.5~6.5 GHz频段范围内S11参数小于-10 dB良好的阻抗匹配,工作带宽内峰值增益为9.3 dBi。

一种小型化人工表面等离激元传感系统——实现自适应和高灵敏的气体检测

Resonantly enhanced dielectric sensing has superior sensitivity and accuracy because the signal is measured from relative resonance shifts that are immune to signal fluctuations.For applications in the Internet of Things(IoT),accurate detection of resonance frequency shifts using a compact circuit is in high demand.We proposed an ultracompact integrated sensing system that merges a spoof surface plasmon resonance sensor with signal detection,processing,and wireless communication.A softwaredefined scheme was developed to track the resonance shift,which minimized the hardware circuit and made the detection adaptive to the target resonance.A microwave spoof surface plasmon resonator was designed to enhance sensitivity and resonance intensity.The integrated sensing system was constructed on a printed circuit board with dimensions of 1.8 cm×1.2 cm and connected to a smartphone wirelessly through Bluetooth,working in both frequency scanning mode and resonance tracking mode and achieving a signal-to-noise ratio of 69 dB in acetone vapor sensing.This study provides an ultracompact,accurate,adaptive,sensitive,and wireless solution for resonant sensors in the IoT.

基于人工表面等离子激元的宽带谐振天线

针对传统微带和介质谐振天线(DRA)带宽较窄和尺寸较大的问题,提出了一种基于人工表面等离子激元波导谐振腔的宽带天线。该天线人工表面等离子激元(SSPPs)波导由对称的H型单元结构组成,谐振腔由同轴探针馈电,利用波导单元偶模和奇模两种模式的色散特性,实现了天线带宽的显著增大。该天线工作频段为8.8~12.4 GHz,相对带宽为33.9%。在工作频带内,天线的辐射效率大于92%,最大增益达到了6.8 dBi。此外,天线为低剖面结构,整体尺寸较小,结构简单,利于各种无线通信和传感系统的集成。