一种基于开口谐振环的高增益宽带双极化天线设计

该文设计并制作了一种基于超材料的高增益宽带双极化天线,该天线由两个正交放置的印刷振子单元、馈电巴伦及金属接地板构成。为了进一步展宽带宽、提高增益,在天线上了加载开口谐振环、互补开口谐振环等超材料结构。测试结果表明,该天线回波损耗小于-10 dB的带宽约为69%(0.98~2.01 GHz),在相同的频带内隔离度大于20 dB。由于开口谐振环的引向作用,天线的辐射特性得到改善,增益最大提高了4.1 dB左右。和已有设计相比,该天线的总体高度减小了约12%。其可以当作独立天线使用,也可用作反射面天线的双极化馈源。     

基于新型互补开环谐振器的基片集成波导滤波器

设计了一种新型的互补开环谐振器(Complementary split ring resonators,CSRR),研究了新型CSRR应用在基片集成波导(Substrate integrated waveguide,SIW)时的频率响应。采用该结构设计并制作了两个SIW滤波器,其中心频率分别为5 GHz和6 GHz,带宽分别为800 MHz和2 GHz,设计和实测结果较为吻合。     

Open‐Ended Waveguide Antenna Using a Single Split‐Ring Resonator

This letter proposes an open‐ended waveguide antenna with a single split‐ring resonator. In contrast to the waveguide antennas incorporating multiple rings reported in a previous study, which exhibited narrow bandwidth, the proposed antenna uses only one ring to achieve broader bandwidth while keeping the aperture small. A single ring has a relatively low quality factor compared to multiple rings. The simulated and measured fractional bandwidth was 4.13% and 4.03%, respectively, which is much broader than the fractional bandwidth of about 1% demonstrated in a previous study. This simple technique can be used in many applications that require small apertures including near‐field probes and array elements.     

基于开环谐振器的新型宽带功率分配器研究*

基于人工电磁材料开环谐振器,提出了一种结构紧凑的新型宽带微带功率分配器.通过在微带线上加载开口谐振环(SRRs)单元,使其在某个频段内呈现色散性质即支持后向波传播,从而实现宽带特性.该结构可简单地通过改变开环谐振器结构参数来调节功率分配器中心频率.测试结果表明,该功分器具有体积小巧、损耗低、易制作并方便与其他电路集成等优势.     

All‐Dielectric Metasurfaces for Simultaneous Giant Circular Asymmetric Transmission and Wavefront Shaping Based on Asymmetric Photonic Spin–Orbit Interactions

The control of polarization and wavefront plays an important role in many optical systems. In this work, a monolayer metasurface is proposed to simultaneously realize circular asymmetric transmission (AT) and wavefront shaping based on asymmetric spin–orbit interactions. Circularly polarized incidence, accompanied with arbitrary wavefront modulation, experiences spin‐selected destructive or constructive interference. An extinction ratio of ≈10:1 and an AT parameter of ≈0.69 at 9.6 µm, as well as a full width half‐maximum of ≈2.9 µm (≈30% of the peak wavelength), are measured with the designed metasurface. These measured results are more than four times of those achieved with previous monolayer chiral structures. As far as it is known, this is the first report on the realization of simultaneous giant AT and arbitrary wavefront modulation with only one metasurface. Due to its fabrication simplicity and the multifunctionality of the designed metasurface, this work may provide a promising route to replace bulky cascading optical components with only one ultrathin metasurface for chiroptical spectroscopy, chiral imaging, optical communication, and so forth.     

Quad‐Band Bandpass Filter Using Quad‐Mode Stub‐loaded Resonators

Compact multi‐band bandpass filters using quad‐mode stub‐loaded resonators are proposed in this letter. Firstly, a novel approach about the mode‐splitting characteristics of the quadruple‐mode resonator is investigated, which can provide dual‐band behavior. Secondly, a quad‐band filter is proposed and designed by cascading two quadruple‐mode resonators; the upper one operates at 1.8/2.4 GHz (GSM‐ and WiMax‐band) and the lower one at 1.57/2.1 GHz (GPS‐ and WCDMA‐band). Finally, the proposed filters have been fabricated. Respectable agreement between simulation and measurement verifies the validity of this design methodology.     

基于互补裂环谐振器的集成波导双工器设计

提出了一种基于圆形互补裂环谐振器的新型基片集成波导双工器。该款双工器工作在C波段,两个通道滤波器的工作频率均低于基片集成波导谐振腔的截止频率,由此达到小型化的目的,通道滤波器的体积较传统基片集成波导滤波器缩小约30%。圆形互补裂环谐振器较方形互补裂环谐振器的小型化效果好,并且更易设计。文中提出了一种新的增加通道隔离度方法,即在两个互补裂环谐振器之间切开一个缝隙。该款双工器已被加工成实物,实测两通道插入损耗为1.75 dB(@3.92 GHz)和1.62 dB(@4.62 GHz),隔离度＞37 dB,实测数据和仿真结果吻合。     

计算多层介质中微带环谐振器谐振频率的频域方法

本文介绍计算多层介质微带环谐振器谐振频率的一种频域方法。它是基于电磁场理论中“反应原理”,由求解不同区域中满足边界条件的波动方程出发,通过傅立叶－汉克尔变换得到频域中的一个广义积分方程。根据该方程的数值结果,可获得各种模式下的谐振频率随第二层介质层厚度及介电常数的变化曲线。与变分法比较,一致性很好。这种微带环谐振器在微波热疗中有着广阔的应用前景,本文结果将对临床应用起到一定的指导意义。     

Coupled Whispering Gallery Mode Resonators via Template‐Assisted Assembly of Photoluminescent Microspheres

This study reports a facile method for the assembly of large, array style, coupled dye‐doped microsphere resonators by template‐assisted, in which an aqueous suspension of colloidal microspheres assemble on a patterned template. By exploiting the high resolution of 3D (two‐photon) lithography derived templates, closely packed large arrays, hundreds to thousands of dimers with controlled gap spacing, only limited by the size of the substrate can be achieved. Dye‐doped emissive microspheres with Q‐factors >2.5 × 10² can be achieved and trapped into predetermined cavity positions, thereby controlling the distance between adjacent microspheres. This design allows to scale down dimer spacing from usual 400 nm for traditional photolithography to very small spacing of 50 nm. It is found that exciting individual microspheres in the ensemble shows intense optical cavity modes, whereas closely coupled pairs show controlled mode splitting. Coupling between photoluminescent microspheres is strongly influenced by the gap distance, with strong coupling, equating to normal mode splitting, arising as the gap distance is reduced below traditional sub‐micrometer scale. The coupled dimer assemblies are promising candidates for advancing the development of large‐area coupled nanophotonic structures, beyond the spatial resolution‐limited photolithographical derived arrays.     

High Performance Millimeter‐Wave Image Reject Low‐Noise Amplifier Using Inter‐stage Tunable Resonators

A Q‐band pHEMT image‐rejection low‐noise amplifier (IR‐LNA) is presented using inter‐stage tunable resonators. The inter‐stage L‐C resonators can maximize an image rejection by functioning as inter‐stage matching circuits at an operating frequency (F_OP) and short circuits at an image frequency (F_IM). In addition, it also brings more wideband image rejection than conventional notch filters. Moreover, tunable varactors in L‐C resonators not only compensate for the mismatch of an image frequency induced by the process variation or model error but can also change the image frequency according to a required RF frequency. The implemented pHEMT IR‐LNA shows 54.3 dB maximum image rejection ratio (IRR). By changing the varactor bias, the image frequency shifts from 27 GHz to 37 GHz with over 40 dB IRR, a 19.1 dB to 17.6 dB peak gain, and 3.2 dB to 4.3 dB noise figure. To the best of the authors' knowledge, it shows the highest IRR and F_IM/F_OP of the reported millimeter/quasi‐millimeter wave IR‐LNAs.     

A novel design of circularly polarised antenna based on metamaterial

This article presents a novel design of circularly polarised microstrip antenna based on a metamaterial reflection plane and a half-wave antenna. The metamaterial is composed of two pieces of substrates coated on one side with split ring resonators. Both the experimental and simulated results show that good circularly polarised radiation performances are obtained. The 10?dB return-loss impedance bandwidth and 3?dB axial ratio bandwidth of proposed antenna are 12% and 7%, respectively, and the gain of proposed antenna compared with the half-wave antenna is improved from 6?dB to 9?dB in the design frequency range.     

基于CSRR的带通滤波器小型化设计

介绍了一种新型的互补开环谐振器(Complementary Split Ring Resonators,CSRR),用此新型谐振器和1/4波长传输线变换器制作了波导带通滤波器.在此基础上为了使滤波器更小型化,设计了挡板结构,改进了滤波器的1/4波长传输线变换器.通过对两种结构的仿真比较得出,新型结构的滤波器在满足设计需...     

High‐Energy Asymmetric Supercapacitor Yarns for Self‐Charging Power Textiles

Rapid growth of electronic textile increases the demand for textile‐based power sources, which should have comparable lightweight, flexibility, and comfort. In this work, a self‐charging power textile interwoven by all‐yarn‐based energy‐harvesting triboelectric nanogenerators (TENG) and energy‐storing yarn‐type asymmetric supercapacitors (Y‐ASC) is reported. Common polyester yarns with conformal Ni/Cu coating are utilized as 1D current collectors in Y‐ASCs and electrodes in TENGs. The solid‐state Y‐ASC achieves high areal energy density (≈78.1 µWh cm^?2), high power density (14 mW cm^?2), stable cycling performance (82.7% for 5000 cycles), and excellent flexibility (1000 cycles bending for 180°). The TENG yarn can be woven into common fabrics with desired stylish designs to harvest energy from human daily motions at high output (≈60 V open‐circuit voltage and ≈3 µA short‐circuit current). The integrated self‐charging power textile is demonstrated to power an electronic watch without extra recharging by other power sources, suggesting its promising applications in electronic textiles and wearable electronics.     

A Highly Crystalline Fused‐Ring n‐Type Small Molecule for Non‐Fullerene Acceptor Based Organic Solar Cells and Field‐Effect Transistors

N‐type organic small molecules (SMs) are attracting attention in the organic electronics field, due to their easy purification procedures with high yield. However, only a few reports show SMs that perform well in both organic field‐effect transistors (OFETs) and organic solar cells (OSCs). Here, the synthesis and characterization of an n‐type small molecule with an indacenodithieno[3,2‐b]thiophene (IDTT) core unit and linear alkylated side chain (C₁₆) (IDTTIC) are reported. Compared to the state‐of‐the‐art n‐type molecule IDTIC, IDTTIC exhibits smaller optical bandgap and higher absorption coefficient, which is due to the enhanced intramolecular effect. After mixing with the polymer donor PBDB‐T, IDTIC‐based solar cells deliver a power conversion efficiency of only 5.67%. In stark contrast, the OSC performance of IDTTIC improves significantly to 11.2%. It is found that the superior photovoltaic properties of PBDB‐T:IDTTIC blends are mainly due to reduced trap‐assisted recombination and enhanced molecular packing coherence length and higher domain purity when compared to IDTIC. Moreover, a significantly higher electron mobility of 0.50 cm² V⁻¹ s⁻¹ for IDTTIC in OFET devices than for IDTIC (0.15 cm² V⁻¹ s⁻¹) is obtained. These superior performances in OSCs and OFETs demonstrate that SMs with extended π‐conjugation of the backbone possess a great potential for application in organic electronic devices.     

Kirigami‐Inspired Self‐Assembly of 3D Structures

Self‐assembly of 3D structures presents an attractive and scalable route to realize reconfigurable and functionally capable mesoscale devices without human intervention. A common approach for achieving this is to utilize stimuli‐responsive folding of hinged structures, which requires the integration of different materials and/or geometric arrangements along the hinges. It is demonstrated that the inclusion of Kirigami cuts in planar, hingeless bilayer thin sheets can be used to produce complex 3D shapes in an on‐demand manner. Nonlinear finite element models are developed to elucidate the mechanics of shape morphing in bilayer thin sheets and verify the predictions through swelling experiments of planar, millimeter‐scaled PDMS (polydimethylsiloxane) bilayers in organic solvents. Building upon the mechanistic understandings, The transformation of Kirigami‐cut simple bilayers into 3D shapes such as letters from the Roman alphabet (to make “ADVANCED FUNCTIONAL MATERIALS”) and open/closed polyhedral architectures is experimentally demonstrated. A possible application of the bilayers as tether‐less optical metamaterials with dynamically tunable light transmission and reflection behaviors is also shown. As the proposed mechanistic design principles could be applied to a variety of materials, this research broadly contributes toward the development of smart, tetherless, and reconfigurable multifunctional systems.     

A Low‐Cost,Self‐Standing NiCo2O4@CNT/CNT Multilayer Electrode for Flexible Asymmetric Solid‐State Supercapacitors

The demand for a new generation of flexible, portable, and high‐capacity power sources increases rapidly with the development of advanced wearable electronic devices. Here we report a simple process for large‐scale fabrication of self‐standing composite film electrodes composed of NiCo₂O₄@carbon nanotube (CNT) for supercapacitors. Among all composite electrodes prepared, the one fired in air displays the best electrochemical behavior, achieving a specific capacitance of 1,590 F g^?1 at 0.5 A g^?1 while maintaining excellent stability. The NiCo₂O₄@CNT/CNT film electrodes are fabricated via stacking NiCo₂O₄@CNT and CNT alternately through vacuum filtration. Lightweight, flexible, and self‐standing film electrodes (≈24.3 µm thick) exhibit high volumetric capacitance of 873 F cm^?3 (with an areal mass of 2.5 mg cm^?2) at 0.5 A g^?1. An all‐solid‐state asymmetric supercapacitor consists of a composite film electrode and a treated carbon cloth electrode has not only high energy density (≈27.6 Wh kg^?1) at 0.55 kW kg^?1 (including the weight of the two electrodes) but also excellent cycling stability (retaining ≈95% of the initial capacitance after 5000 cycles), demonstrating the potential for practical application in wearable devices.     

An Asymmetric Iron‐Based Redox‐Active System for Electrochemical Separation of Ions in Aqueous Media

Electrochemically mediated redox‐active processes are gaining momentum as a promising liquid‐phase separation technology. Compared to conventional systems, they offer potential benefits, such as smaller energy footprints, nondestructive operation, reversibility, and tunability for specific analyte removal, with clear applications to societal and industrial challenges like water treatment and chemical synthesis. An asymmetric Faradaic cell heterogeneously functionalized with a metallopolymer at the anode and a hexacyanoferrate material at the cathode is presented for the first time. The redox‐active species' iron centers enhance the electrosorption of heavy metal oxyanions with up to 98% removal in the ppb range, and offer tunable operating windows as low as ≈0.1 V at ≈1 A m^?2. By avoiding water splitting, the hexacyanoferrate cathode imparts additional advantages, namely a four‐fold reduction in adsorption energy requirements, full suppression of solution pH increase, and the ability to capture redox‐active catalytic anions such as polyoxometalates without altering their bulk oxidation state. This hybrid framework of a polymeric ferrocene anode and crystalline hexacyanoferrate cathode allows for simultaneous and synergistic uptake of anions and cations, respectively, creating a new asymmetric scheme for water‐based separations, with foreseeable future extension to fields such as ion‐sensing, energy storage, and electrocatalysis.     

Magnetically Modulated Pot‐Like MnFe2O4 Micromotors: Nanoparticle Assembly Fabrication and their Capability for Direct Oil Removal

This work demonstrates a simple‐structured, low‐cost magnetically modulated micromotor of MnFe₂O₄ pot‐like hollow microparticles as well as its facile, versatile, and large‐scale growing‐bubble‐templated nanoparticle (NP) assembly fabrication approach. In this approach, the hydrophobic MnFe₂O₄@oleic acid NPs in an oil droplet of chloroform and hexane assembled into a dense NP shell layer due to the hydrophobic interactions between the NP surfaces. With the encapsulated oil continuously vaporizing into high‐pressured gas bubbles, the dense MnFe₂O₄ NP shell layer then bursts, forming an asymmetric pot‐like MnFe₂O₄ micromotor by creating a single hole in it. For the as‐developed simple pot‐like MnFe₂O₄ micromotor, the catalytically generated O₂ molecules nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer convex surface, resulting in continuous ejection of O₂ bubbles from the open hole to propel it. Dexterously integrating the high catalytic activity for H₂O₂ decomposition to produce O₂ bubbles, excellent magnetic property with the instinctive surface hydrophobicity, the MnFe₂O₄ pot‐like micromotor not only can autonomously move in water media with both velocity and direction modulated by external magnetic field but also can directly serve for environmental oil removal without any further surface modification. The results here may inspire novel practical micromotors.     

Design of an Ultra‐Wideband Antenna Using a Ring Resonator with a Notch Function

This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi).