基于同向开口双环的双通带左手材料研究

为了改进传统的开口谐振环-导线（ SRRs-wire）结构电磁特性,利用不同大小的开口谐振环所产生不同负磁谐振频率点的特点,设计了同向开口双环的SRRs-wire结构,并给出了其等效电磁参数反演结果。通过增加其单元结构的金属短线的个数实现了双通带左手特性;同时通过改变外环为U型环降低了内外环的相互耦合。利用内外谐振环间具有弱耦合的特性,提高了高频左手通带的带宽,同时可以较方便地调节双通带工作频率点,具有很好的可调性。     

基于I型谐振结构的太赫兹超材料吸收体传感器研究

基于“Ｉ”型谐振结构的太赫兹超材料吸波器可在0.523THz处产生吸收率为99.5%,谐振峰半高宽为14GHz,品质因数为37的极窄吸收峰,具有较强的频率选择性。在待测分析物厚度为8μｍ,折射率范围为1.0~ 1.8的情况下,该太赫兹超材料吸波器的折射率灵敏度为80.7GHz/RIU,可作为高灵敏度的折射率传感器实现对待测分析物的检测,对谐振单元表面覆盖不同待测分析物情况下的电磁场分布进行仿真分析,揭示了折射率传感器的传感机理。 此外,仿真研究了待测分析物厚度对该超材料吸收体传感器谐振频率及折射率灵敏度的影响。基于“Ｉ”型谐振结构的太赫兹超材料吸波器具有结构简单、品质 因数高、折射率灵敏度高等特点,在无标记的高灵敏度生物医学传感中具有潜在的应用前景。     

基于金属—有机骨架材料的C反应蛋白传感器研制

在常温下合成了Au纳米颗粒负载的超纳米结构金属有机骨架化合物(Au NPs/SNHKUST—1),并以其为标记材料标记C反应蛋白抗体.同时合成了中空状石墨烯纳米材料和Au纳米颗粒作为固定基质,制备了夹心型的C反应蛋白免疫传感器.通过检测标记物对H2 O2还原反应的催化电流,实现了对C反应蛋白的定量测定.传感器在C反应蛋白浓度为0.2~200 ng/mL的范围内线性良好的,线性相关系数R2=0.9947,检测下限为0.05 ng/mL,为C反应蛋白测定提供了一种新的简单快速的检测方法.     

基于CRLH—TL及CSRR的带通滤波器

首次提出一种复合左右手传输线零阶谐振器及互补谐振环的新型带通滤波器.设计方法利用左右手复合传输线的独有特性,即零阶谐振器中心频率与谐振器长度无关,能在特定非零频率上得到无限波长的特点,来构造环形滤波器,并且地板蚀刻了长方形互补谐振环结构.设计过程中使用了AnsoftHFSS软件进行全波仿真,经过多次仿真,通过调节参数大小优化设计,最终结果得到中心频率为1.85GHz、带宽为0.1GHz的新型带通滤波器.在达到同样效果的前提下,减小尺寸,单个谐振器与传统相比体积减少了近80%,长方形CSBR还提高了传输特性.上述结构的实现对于左手材料在微波器件中的发展有一定的促进作用,进一步扩大了左手材料的应用范围.     

纳米金刚石颗粒的衬底增强效应研究

金刚石氮空位(NV)色心由于具有发光稳定、无毒、量子特性已成为最有发展前景的生物荧光标记材料.为进一步提高生物荧光标记检测和识别的分辨率,结合表面荧光增强效应,提出了结合Si,SiO2,金属三种不同折射率的材料来实现对NV色心荧光信号的增强特性.测试结果表明:金刚石结构与金属材料相结合后荧光增强最大达到17.71倍,进一步表明荧光增强机理,为提高生物荧光标记检测和识别灵敏度与分辨率提供了研究基础.     

Si基微环谐振腔化学传感检测方法研究

提出了一种非标记光化学传感检测方法：光波导谐振谱检测,通过感应环形波导表面有效折射率变化进行化学传感;理论分析,并结合光学测试系统,利用此方法实现了微环谐振腔结构对NaCl离子、结晶紫分子溶液的在线浓度测量,实验得到：其检测灵敏度分别达181.47 pm/10－2,227 nm/（ mol·L－1）,证明了该方法可以应用于化学溶液检测领域。     

基于高性能光电材料和核酸信号放大策略的光致电化学生物传感器概述

1839年Edmond Becquerel首次发现了光电效应，自此光致电化学（photoelectrochemical,PEC）蓬勃发展。通常情况下，PEC过程是指有机/无机光电活性材料在光照射下吸收光子，电荷随之发生分离和转移，实现光-电转换过程，界面处产生的电子-空穴对（e--h+）将引起分子或离子的氧化还原反应。光致电化学与生物分析的结合开创了PEC生物分析的新兴领域，PEC生物分析主要包含两个关键要素：光电活性材料和生物识别元件，其中，光电活性材料用于产生检测信号，生物识别元件主要为酶、抗体和核酸等，它与检测目标物相关。PEC生物分析原理为识别元件与其相应的目标物之间发生生物相互作用，引起光电流/光电压的变化，该过程以光作为输入信号，电流/电压作为检测信号，这种不同的能量形式也赋予PEC生物分析低的背景信号和较高的检测灵敏度。目前，PEC生物传感在疾病早期诊断、环境污染物监测、食品安全分析等方面显现出潜在的应用前景。而PEC生物传感器的检测性能很大程度受到材料光电性能的影响，因此，提高材料光电转换和载流子迁移效率是有效提高传感器性能的关键。另一方面，待检测目标物浓度一般为痕量甚...     

一种具有宽带双极化低散射特征的微带阵列天线

针对阵列天线宽带散射缩减设计进行研究,设计了一种基于无源对消技术的低散射阵列天线,该新型微带阵列天线在宽频带内具有双极化低雷达散射截面（RCS, Radar Cross Section）性能;对基于两种散射性能不同的单元组成阵列的RCS性能进行了理论研究,进行了单元的散射幅度和相位对阵列RCS的影响分析;提出了一种加载T型缝隙的新型微带天线结构,该单元结构的辐射性能与散射性能能够进行独立调控和综合优化,该单元与传统微带贴片单元具有相似的辐射特性,并可在宽频带（带内和带外）内与传统微带单元产生有效相位差;将传统微带单元和加载T型缝隙的新型微带单元组成4×4阵列天线,仿真结果表明,提出的阵列天线在3GHz～7GHz（相对带宽80%）频带内实现了同极化RCS缩减,在3.3GHz～7GHz（相对带宽71.8%）频带内实现了交叉极化RCS缩减,缩减峰值分别为16.3dB和36.3dB,带内RCS缩减均值分别为14.1dB 和17.6dB;与传统微带阵列天线相比,提出的阵列天线增益下降小于0.1dB;提出的微带阵列天线具有高效率辐射和宽频带双极化低散射性能,为低散射阵列天线设计提供了新的思路。     

用于腺苷检测的基于级联扩增核酸适体电化学传感界面的构建研究

该文报道了一种基于酶级联扩增的电化学核酸适体检测腺苷的新方法。当腺苷存在时,滚环扩增的引物通过E.coli DNA连接酶的作用与通过巯基组装在金电极上的固定探针连接。在pHi29 DNA聚合酶的作用下,滚环扩增反应进行并产生一条与环形探针完全互补的长的单链,然后将大量金纳米粒子标记的核酸探针与滚环扩增的产物杂交。该传感界面电化学行为的结果表明,通过酶级联扩增的方法提高了检测腺苷的阻抗响应灵敏度,且选择性和重现性良好。用于腺苷的检测时,其线性范围为2.0μmol/L~100μmol/L,最低检测浓度为2.0μmol/L,表明该传感界面的设计可作为一种通用方法而有望用于其它目标物的检测。     

基于信号放大技术及DNA功能材料的生物传感器研究

临床相关分子（包括小分子、核酸和蛋白质）具有许多生物学功能,包括存储和传递遗传信息、调节生物活动、运输小分子和催化反应等等。此外,它们还可以作为许多疾病诊断的生物标记物。因此,这些小分子的精确检测对于疾病的诊断和治疗具有十分重要的意义。生物传感器可以通过输出的信号对分析物进行定量分析,同时具有快速、灵敏和选择性高等特点,故而被广泛应用。近年来,随着DNA纳米技术的兴起,将DNA功能材料用于构建生物传感器对其灵敏度和特异性等性能的提高具有重要的意义。该论文将目标物循环扩增,杂交链式反应,滚环扩增及级联催化放大等信号放大技术和DNA功能材料相结合以增大信号响应,并以此构建不同的新型灵敏生物传感器。     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

A novel dual‐band bandpass filter using co‐directional split ring resonators with closely spaced passbands and wide upper stopband

In this article, interdigital capacitor loaded co‐directional split ring resonators (CDSRRs) and their dual‐band bandpass filter applications are proposed. The proposed resonator is formed by nested open loop resonators having open ends at the same place unlike conventional split ring resonators (SRRs). In addition, the inner open loop resonator has interdigital capacitor located between the open ends. The proposed resonator exhibits dual resonance behavior with a small center frequency ratio. Both of resonance frequencies can be controlled due to the changes in the interdigital capacitor and the electrical length of the outer resonator. A dual‐band microstrip bandpass filter is designed by using the proposed CDSRR. Two CDSRRs are used to obtain two poles in each passband. Overall electrical length of the designed filter is 0.23 λ_g × 0.14 λ_g (0.0329 λ_g²), where λ_g is the guided wavelength for the used substrate at the lowest passband center frequency of 1.8 GHz. A small center frequency is obtained by adjusting the second passband at 2.27 GHz. A very wide upper stopband, closely spaced passbands, low insertion losses and high selectivity at both passbands can be obtained by means of the proposed structure. The designed filter was also fabricated and tested. The measured results show a very good agreement with the predicted results.     

A metamaterial hepta‐band antenna for wireless applications with specific absorption rate reduction

Present article embodies the design and analysis of slotted circular shape metamaterial loaded multiband antenna for wireless applications with declination of SAR. The electrical dimension is 0.260 λ × 0.253 λ × 0.0059 λ (35 × 34 × 0.8 mm³) of proposed design, at lower frequency of 2.23 GHz. The antenna consists of circular shape rectangular slot as the radiation element loaded with metamaterial split ring resonator (SRR) and two parallel rectangular stubs, etched rectangular single complementary split‐ring resonator (CSRR) and reclined T‐shaped slot as ground plane. Antenna achieves hepta bands for wireless standards WLAN (2.4/5.0/5.8 GHz), WiMAX (3.5 GHz), radio frequency identification (RFID) services (3.0 GHz), Upper X band (11.8 GHz—for space communication) and Lower K_U band (13.1 GHz—for satellite communication systems operating band). Stable radiation patterns are observed for the operating bands with low cross polarization. The SRR is responsible for creating an additional resonating mode for wireless application as well as provide the declination in SAR about 13.3%. Experimental characteristic of antenna shows close agreement with those obtained by simulation of the proposed antenna.     

Low profile four‐port super‐wideband multiple‐input‐multiple‐output antenna with triple band rejection characteristics

A quad‐port planar multiple‐input‐multiple‐output (MIMO) antenna possessing super‐wideband (SWB) operational features and triple‐band rejection characteristics is designed. The proposed MIMO configuration consists of four modified‐elliptical‐self‐complementary‐antenna (MESCA) elements, which are excited by tapered co‐planar waveguide (TCPW) feed lines. A radiator‐matched complementary slot is present in the ground conductor patch of each MESCA element. The proposed MIMO antenna exhibits a bandwidth ratio of 36:1 (|S₁₁| < ?10 dB; 0.97‐35 GHz). Further, a step‐like slit‐resonator is etched in the radiator to eliminate interferences at 3.5 GHz. A hexagonal shaped complementary split ring resonator (CSRR) is also loaded on the MESCA radiator to remove interferences at 5.5 and 8.5 GHz. The MIMO antenna is fabricated on FR‐4 substrate of size 63 × 63 mm² and experimental results are found in good agreement with the simulated results. The MIMO antenna exhibits inter‐element isolation >17 dB and envelope correlation coefficient (ECC) <0.01 at all the four ports.     

Quad notch UWB antenna using combination of slots and split‐ring resonator

A novel coplanar waveguide fed UWB antenna with quad notch band characteristics has been proposed in this work. The antenna layout is designed based on a combination of well‐known geometrical shapes: a half ellipse patch, rectangle, and triangle. The shape of the ground plane is partially tapered rectangular. The overall dimension of the antenna is 41.5 × 32 mm. The antenna uses three U‐shaped slots at the top surface to create three notched band characteristics. A split‐ring resonator is then introduced at the bottom surface of the antenna. With the integration of split‐ring resonator at the bottom surface, an additional notch band at 7.25 to 7.75 (6.7%) GHz is created in the antenna. The designed antenna has an operating impedance bandwidth (VSWR ≤2) ranges from 3.03 to 12.34 GHz except in quad frequency stop bands of 3.3 to 3.7 (11.4%), 5.15 to 5.35 (3.8%), 5.725 to 5.825 (1.7%), and 7.25 to 7.75 (6.7%) GHz. The proposed antennas are successfully designed, prototyped, and measured. The simulated and measured results are extensively studied and discussed. Correlation between the time‐domain transmitting antenna input signal and the received antenna output signal is calculated in order to ensure that the proposed antenna can be used in pulse‐communication systems. This antenna finds applications in medical imaging, military radar systems, and other common UWB applications.     

A compact energy harvesting multiband rectenna based on metamaterial complementary split ring resonator antenna and modified hybrid junction ring rectifier

This article presents an improved wireless energy harvesting multiband rectifying antenna. The proposed design is based on an original optimized bidirectional complimentary split ring resonator (CSRR) metamaterial multiband antenna and a modified hybrid junction ring rectifier with four rectifying branches. It harvests the ambient radiofrequency radiations at GSM, 1.8 GHz; UMTS, 2.1 GHz; WiFi, 2.45 GHz; and 4G‐2.6 GHz GSM bands. The created prototypes are printed on a 1.57‐mm‐thickness FR4 substrate and achieve the needed dimensional optimization in both antenna and rectifier. The CSRR antenna accomplished a maximum harvesting realized gain of 2.41, 2.26, 1.58, and 2.69 dB on the aforementioned frequency bands, respectively, 63.75% of antenna size reduction, and 23.62% rectifier size reduction regarding the conventional designs. The hybrid ring junction is used to independently match the subrectifiers at each frequency band. The realized rectenna has been accurately tested in both controlled and outdoor environments, achieving a 67.6% peak efficiency at 1.8 GHz frequency band for an input power level of 10 dBm. It powered up a digital batteryless watch in the outdoor experiment.     

Perturbed Sierpinski carpet resonator and its usage in compact dual and triple band bandpass filters

In this paper, perturbed Sierpinski carpet fractal shaped resonator is characterized and applied in the design of multiband band pass filters (BPFs). The route to achieving compact multimode resonators starting from the Sierpinski carpet fractal shaped resonator is detailed. The proposed resonators are used to demonstrate two topologies of dual band bandpass filters with passband center frequencies at 3.5 GHz as well as 5.5 GHz, respectively. Both the designs exhibit nearly identical passband bandwidth. In the second design, it is observed that the second passband gets slightly shifted towards 5.85 GHz. However, with edge loading this shift is nullified. A scaled down version of the same resonator is designed and three such resonators are interdigitally coupled in conjunction with complementary split ring resonators to exhibit a novel technique of achieving compact triband bandpass filter. All designs have acceptable passband insertion loss in the respective bands. Accessories are used to improve passband selectivity in all designs and also a wide stop band till 10 GHz is obtained. Fabrication prototypes for all the variants are realized with simulated and measured results in good agreement. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:418–425, 2016.     

Isolation enhancement of rectangular dielectric resonator antennas using wideband double slit complementary split ring resonators

A wideband epsilon‐negative structure is employed as one‐layer and two‐layer isolators to reduce mutual coupling in multiple‐input multiple‐output systems composed of two E‐coupled rectangular dielectric resonator antennas. The proposed unit cell with ?15 dB bandwidth for S₂₁ extending from 1970 to 3317 MHz, is a double slit complementary split ring resonator etched on the ground plane of a stripline. Each layer is composed of a 2 × 3 array of the suggested unit cell. Reduction in isolation of more than 11 dB for the one‐layer case and higher than 20 dB for the two‐layer case are measured within the frequency range of 2.604 to 2.64 GHz which includes WiMAX. The highest isolation level of 36 dB is realized at 2.868 GHz. The impedance matching, gain, radiation efficiency, and envelope correlation are improved compared to the original case. A prototype is designed, fabricated, and tested. Simulation data and measurement results are in good agreement.     

Modified octahedron shaped antenna with parasitic loading plane having dual band notch characteristics for UWB applications

The design of a compact modified octahedron shaped dual band notched ultra wide‐band antenna is presented in this article. The impedance bandwidth of the designed antenna has been enhanced by modifying the shape of the radiator by introducing fractal geometry and a modified ground plane. The proposed antenna offered an impedance bandwidth of 2.4 GHz–19.5 GHz (156% Fractional bandwidth). Two rectangular split ring resonator structures are introduced in the radiator to achieve two notched bands which ranges from 3.3 GHz to 3.7 GHz (WiMAX) and 5.15 GHz–5.85 GHz (WLAN) band. The antenna gain varies from 1 to 4 dBi over the operating band except the notched bands. The overall dimension of the designed antenna has a compact size of 33 × 40 mm². The experimental and simulation results are in good agreement. The proposed antenna has wider bandwidth and smaller dimension over the already reported in the literature. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:426–434, 2016.