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Now showing items 1 - 16 of 93

  • Decoupling antenna array with X-shaped strip

    Zou, Xiao-Jun   Wang, Guang-Ming   Wang, Ya-Wei   Li, Hai-Peng  

    Manipulating mutual coupling between antenna array elements is always a critical essential in designing phased arrays. In this article, an X-shaped strip is applied to decouple a five-element E-plane microstrip antenna array, whose adjacent elements' center-to-center spacing is only 0.45 lambda(0). Simulation and measurement results reveal that the proposed array employing the loaded structure exhibits excellent decoupling capability, as in comparison to the reference array, impedance of every port is well matched, mutual coupling between both adjacent elements and nonadjacent ones is efficiently reduced and radiation patterns of every individual patch are markedly corrected. Besides, when beam scanning is performed, the proposed array is equipped with higher gain and lower SLL. The X-shaped strip predicts a promising application in phased array and a large-scale array.
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  • Multifunctional Full-Space Metasurface With Complete Polarization Control

    Zhang, Chi-Ben   Wang, Guang-Ming   Li, Hai-Peng   Zhang, Xin   Zou, Xiao-Jun   Ji, Wen-Ye   Wang, Can-Yu  

    The full-space metasurface generally integrates the functions of traditional reflection and transmission metasurfaces. In this paper, a meta-film with ring slot is used to reflect and propagate complete-polarization waves with lower and higher frequency bands, respectively. Then meta-atoms can be placed up and down of the ring slot to achieve different functions of reflection and transmission. As a verification of this concept, reflection-mode with the function of radar cross section reduction is implemented by using chess-board meta-atoms while the transmission-mode with deflection function is obtained by using geometric elements. Our findings provide a way of designing full-space metasurface with complete-polarization control.
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  • Analysis and Design of a Broadband Metasurface-Based Vortex Beam Generator

    Guo, Wen-Long   Wang, Guang-Ming   Li, Hai-Peng   Hou, Hai-Sheng   Xu, He-Xiu  

    Metasurface-based vortex beam generators are very promising and applicable to enhance transmission data capacity in wireless communication system. However, most designs to date are ceased to predict their far-field characteristic, which is actually in demand when applied to wireless communication. Here, we find for the first time a deterministic and robust strategy to fastly estimate the exact far-field patterns and gain limit of a vortex beam based on the theoretical analysis of aperture field with spiral phase profile. For verification, a broadband metasurface-based vortex-beam generator based on geometric phase is designed, numerically calculated and experimentally measured at microwave regime. Excellent agreements are observed among far-field results obtained based on the proposed method, numerical simulations and experimental measurements, firmly demonstrating the validity and correctness of the proposed strategy. Such a deterministic and robust strategy of predicting far-field characteristics of a vortex beam may pave the way for its applications in many engineering scenarios, such as conical beam design, wireless communication, et al.
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  • A novel uniplanar wideband magneto-electric dipole antenna element

    Shuai, Chen-Yang   Wang, Guang-Ming   Wang, Ya-Wei  

    A novel uniplanar wideband magneto-electric dipole antenna element is proposed in this paper. The proposed antenna is composed of the conventional bow-tie radiation patch as an electric dipole, a semi-circular loop, which works as a magnetic dipole, a coplanar ground plane, two directors with different lengths for enhancing gain, and a microstrip-to-coplanar stripline transition balun. The designed antenna adopts a small-size coplanar ground plane to achieve a uniplanar structure. Consequently, this method reduces the space size immensely and makes the antenna suitable for the array application. In addition, a tapered slot structure is utilized to improve impedance matching. The prototype of the proposed antenna was fabricated and measured. The measured results keep in good accordance with the simulated ones. The simulated results show that the proposed antenna obtains a broad impedance bandwidth of 60.5% from 2.25 to 4.20 GHz (voltage standing wave ratio [VSWR] 2) which can be applied for wireless local area network (WLAN) (2.4-2.484 GHz), worldwide interoperability for microwave access (WiMAX) (2.5-2.69/3.4-3.69 GHz), and long term evolution (LTE) (2.5-2.69 GHz). Meanwhile, the stable gain, low cross-polarization, stable unidirectional radiation patterns, and low back lobe are obtained within the operating frequency band. The array composed of the proposed antenna elements is also investigated in this paper.
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  • A Novel Planar Printed Dual-Band Magneto-Electric Dipole Antenna

    Shuai, Chen-Yang   Wang, Guang-Ming  

    In this paper, a novel planar printed dual-band magneto-electric dipole antenna is proposed. The proposed antenna is composed of a conventional bow-tie patch as an electric dipole, a semicircular loop that operates as a magnetic dipole, a coplanar ground plane, and a wideband microstrip-to-coplanar-stripline transition balun. By etching a pair of complementary capacitively loaded loop slots on the bow-tie radiation patch, a notched band is introduced to form the dual-band antenna. And a coplanar ground is adopted to make the entire antenna become a planar printed structure. Additionally, the proposed antenna loads the periodical interdigital capacitance structure on the semicircular loop for the purpose of making the current flowing along the loop maintain the same phase and improving the performances of the magnetic dipole. The proposed antenna was fabricated and measured. The measured results keep in good accordance with the simulated ones. Consequently, the proposed antenna achieves a dual-band operation at 2.37 similar to 2.82 GHz (17.3%) and 3.14 similar to 4.10 GHz (26.5%) with the Voltage Standing Wave Ratio (VSWR) less than 2, so it can be applied for WLAN (2.4-2.484 GHz) and WiMAX (2.5-2.69 GHz/3.4-3.69 GHz). Meanwhile, the stable gain, symmetrical, and stable unidirectional radiation patterns, low cross polarization, and low back lobe are also obtained at the dual bands.
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  • Substrate integrated low-profile dual-band magneto-electric dipole antenna

    Shuai, Chen-Yang   Wang, Guang-Ming  

    In this article, a novel substrate integrated low-profile dual-band magneto-electric (ME) dipole antenna is proposed. The entire antenna is constructed by four-layer printed circuit boards (PCBs). Consequently, the height of the proposed antenna is decreased from 0.25(0) to 0.11(0) ((0) is the free-space wavelength at 5.5GHz). By introducing rectangular patches with different sizes as electric dipoles, dual operating bands are achieved. Meanwhile, for the purpose of improving the impedance matching at the lower frequency band, a pair of complementary split-ring resonators (CSRRs) is etched on the larger rectangular patches. Moreover, the short walls composed of plated through holes operate as a magnetic dipole. The antenna is fed by an equivalent wideband microstrip-to-parallel stripline balun. The results show that the antenna obtains dual bandwidths of 4.31-4.71GHz (8.8%) and 5.07-5.89GHz (14.9%) with VSWR <2, which can be applied for C-band and 5G WiFi. Over the dual operating bands, stable gain and unidirectional radiation patterns with low polarization and low back lobe are also obtained.
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  • Regulatory Effect of General Anesthetics on Activity of Potassium Channels.

    Li, Yan   Xu, Jie   Xu, Yun   Zhao, Xiao-Yun   Liu, Ye   Wang, Jie   Wang, Guang-Ming   Lv, Yan-Tian   Tang, Qiong-Yao   Zhang, Zhe  

    General anesthesia is an unconscious state induced by anesthetics for surgery. The molecular targets and cellular mechanisms of general anesthetics in the mammalian nervous system have been investigated during past decades. In recent years, K+ channels have been identified as important targets of both volatile and intravenous anesthetics. This review covers achievements that have been made both on the regulatory effect of general anesthetics on the activity of K+ channels and their underlying mechanisms. Advances in research on the modulation of K+ channels by general anesthetics are summarized and categorized according to four large K+ channel families based on their amino-acid sequence homology. In addition, research achievements on the roles of K+ channels in general anesthesia in vivo, especially with regard to studies using mice with K+ channel knockout, are particularly emphasized.=20
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  • Microstrip Antenna Array of Connected Elements Using X-Shaped Connection Line

    Zou, XiaoJun   Wang, Guang-Ming   Wang, Yawei  

    Unlike multitudinous research works hammering at decoupling closely spaced antenna array, this letter introduces an X-shaped connection line to strengthen mutual coupling between array elements. Through adding the structure, a five-element linear E-plane microstrip antenna array exhibits comparable performance to a fully fed one, obtaining high broadside gain and low sidelobe level (SLL) and costing less owing to fewer excitations and more simplified feeding network. Also, the structure is valid for a wide range of element spacing. A typical microstrip antenna array at 5.7 GHz is fabricated to verify the feasibility, which exhibits 15.71 dBi broadside gain and -12.18 dB SLL. The results reveal its promising application in a larger array or two-dimensional array.
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  • Wavenumber-Splitting Metasurfaces Achieve Multichannel Diffusive Invisibility

    Xu, He-Xiu   Zhang, Lei   Kim, Yongjune   Wang, Guang-Ming   Zhang, Xiao-Kuan   Sun, Yunming   Ling, Xiaohui   Liu, Haiwen   Chen, Zhining   Qiu, Cheng-Wei  

    The emerging invisibility schemes mainly adopt transformation optics, scattering cancellation, light diffusion, and metasurface-based phase restoration techniques. However, those aforementioned invisibility achievements natively depend on the predefined curvature, polarization, frequency, and/or angle of the incident wave. Here, an invisibility strategy of using an ultrathin parabolic-phase metasurface and its applications to achieve diffusive invisibility for dual-polarization channels and multifrequency channels is reported. Such strategy can intrinsically split the wavenumber of the scattering wave and therein is termed as wavenumber-splitting metasurface. For verification, two proof-of-concept examples are experimentally characterized. The first prototype manifests dual-polarized near-isotropic diffusive scattering immune from wide-angle incidences. The second demonstration exhibits bifunctionality of combined diffusive invisibility and vortex scattering in dual-polarization channels. In both cases, theoretical, numerical and experimental results agree well, illustrating a well-separated triple-band versatile scattering behavior. This approach addresses the fundamental issue of real invisibility under bistatic detection without complex optimization, thanks to the physical essence of numerous splitting wave vectors. Such strategy opens an upstream way to realize invisibility as well as holding the potentials for downstream applications such as stealth and camouflaging devices.
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  • Polarization-independent broadband meta-surface for bifunctional antenna

    Cai, Tong   Wang, Guang-Ming   Xu, He-Xiu   Tang, Shi-Wei   Liang, Jian-Gang  

    Functional integration is crucial and has become a research interest in recent years; however, available efforts suffer from low efficiency and narrow operating bandwidth. Here, we propose a novel strategy to design bifunctional meta-surface with high efficiency and largely enhanced bandwidth in reflection geometry. For demonstration, we designed and fabricated a bifunctional meta-surface which enables both focusing and anomalous reflection under different polarizations. The working bandwidth is significantly extended by using the dual-resonant three-turn meander-line resonator (TMLR) element which provides an almost consistent phase response within a large frequency interval. For potential applications, we engineered a bifunctional antenna by launching the designed meta-surface with proper feed sources. Numerical and experimental results coincide well, indicating bifunctionalities of high gain pencil-beam radiation (reflectarray) and beam steering radiation with comparable performances. Our results can stimulate the realizations of high-performance meta-surfaces and antenna systems. (C) 2016 Optical Society of America
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  • A novel combined structure for decoupling E/H-plane microstrip antenna array

    Zou, Xiao-Jun   Wang, Guang-Ming   Wang, Ya-Wei  

    A novel structure combined of an I-shaped microstrip line and eight slots etched from the ground plane is proposed to decouple both E-plane and H-plane antenna arrays. Five types of antenna arrays at 5.25 GHz with different linear placements are discussed for the first time and the decoupling structure is valid to them all. The edge-to-edge distances of the H-plane arrays and the E-plane arrays are 0.09 0 and 0.17 0(,) respectively. Simulated and measured results indicate that the combined structure can effectively reduce the mutual coupling, with the maximum values reaching to 22.62, 28.41, 21.04, 22.33, and 26.04 dB for five types, respectively. The proposed structure is potential in the application of multielement arrays and communication MIMO system.
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  • A 1.12 GHz TO 2 GHz wide-tuning-range VCO with dynamic coupling structures

    Xiang, Yong-Bo   Wang, Guang-Ming   Zhang, Xu-Chun   Liang, Jiangang  

    This paper presents a continuous wide-tuning-range VCO with 56.4% frequency tuning ratio (FTR). Both a dynamic coupling resonator structure and a dynamic feedback amplifying circuit are proposed to maintain the wide-tuning range for the VCO. The dynamic coupling promises stable loaded Q factor and wider tuning range, while the dynamic feedback amplifying circuit assured the oscillating condition across the large frequency tuning range. There are three voltage tunable structures in the proposed, all of which are controlled by the same tuning voltage, so it is easy to be controlled and can be phase locked by a phase-lock-loop (PLL). The VCO results in a tuning range from 1.12 GHz to 2.00 GHz at 0 approximate to +5 V tuning voltage. The measured output power is 4.0 approximate to 6.37 dBm within the tuning range. The measured phase noise is -94.24 approximate to -98.66 dBc/Hz at 100 kHz frequency offset and -118.07 approximate to -123.41 dBc/Hz at 1 MHz frequency offset respectively within the tuning range. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1525-1529, 2016
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  • Ultra-Wideband E-Plane Monopulse Antenna Using Vivaldi Antenna

    Wang, Ya-Wei   Wang, Guang-Ming   Yu, Zhong-Wu   Liang, Jian-Gang   Gao, Xiang-Jun  

    An ultra-wideband (UWB) E-plane monopulse antenna working in the frequency range from 3.1 to 10.6 GHz is proposed. The UWB E-plane two-element array is constructed using Vivaldi antennas. By shortening the adjacent tapered lines of the two Vivaldi antennas and using corrugated edges, sum and difference characteristics of the array are improved. The UWB monopulse comparator is a multilayer planar magic T consisting of an UWB 90 directional coupler and two UWB 45 degrees phase shifters in series. By integrating the array and the comparator, the UWB E-plane monopulse antenna is designed and fabricated with the low-cost PCB process. In the frequency range from 3.1 to 10.6 GHz, the sum gain is measured as more than 10.1 dBi, the sidelobe level less than -13.1 dB, and the null depth greater than 22.5 dB. The good sum and difference characteristics obtained make the proposed UWB E-plane monopulse antenna desirable for target detecting and tracking.
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  • Dual-Mode Transmissive Metasurface and Its Applications in Multibeam Transmitarray

    Xu, He-Xiu   Cai, Tong   Zhuang, Ya-Qiang   Peng, Qing   Wang, Guang-Ming   Liang, Jian-Gang  

    A novel triple-layer dual-mode meta-atom wherein an H-shaped structure is combined with a pair of symmetric patches is proposed. The composite structure substantially lowered the operation frequency, and balanced phase agility with transmission magnitude bandwidth. The transmission phase limit of the proposed composite structure approaches the theoretical limit. Because this structure has appealing features, we employed a set of these ultrathin meta-atoms to implement the phase distribution of an optimized array using the alternating projection method. An X-band single-feed quad-beam transmitarray consisting of 25 x 25 elements, each carefully designed to exhibit the desired transmission phase, was designed, simulated, physically implemented, and measured. Feeding the meta-array using a horn at its focus, four-beam radiation patterns with satisfactory sidelobe levels and gain were numerically and experimentally demonstrated. The peak gain was found to be 18.8 dB at 9.6 GHz, and the aperture efficiency was calculated as 38.3%. Moreover, the half-power beamwidth of the array antenna was approximately 7 degrees, which was 50 degrees narrower than that of a bare feed horn. Moreover, the gain of each beam was higher than 17 dB in all studied cases, which was at least 7 dB higher than that of a bare feed horn.
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  • High-Performance Transmissive Meta-Surface for C-/X-Band Lens Antenna Application

    Cai, Tong   Wang, Guang-Ming   Liang, Jian-Gang   Zhuang, Ya-Qiang   Li, Tang-Jing  

    Conventional multiband transmissive devices suffer from strong interaction among different working frequencies, complex configurations, and low efficiencies. We propose a novel strategy to design high-performance dual-band transmissive meta-surfaces by using anisotropic ABBA systems (a four-layer system with identical structures in layers 1 and 4, and another group of identical structures in layers 2 and 3). The ABBA element provides a new freedom to enhance the transmission and suppress the fluctuations by tuning the coupling among cascaded layers. Dual-band operating property is performed by employing the polarization-related electromagnetic response. A well-designed transmissive meta-surface, operating at f(1) =3D 6.5 GHz and f(2) =3D 10.5 GHz, consists of 13 x 17 ABBA elements with parabolic phase distributions. Good focusing effects with the same focal length and small reflection are observed at both frequencies under different polarizations. For practical applications, a dual-band lens antenna (LA) is implemented by launching the meta-lens with a self-made Vivaldi antenna. Numerical and experimental results coincide well, indicating that the proposed LA is better in many aspects such as high radiation gain, comparable aperture efficiencies to other designs in literature, and having a simple fabrication process. The finding opens up a new avenue to design high-performance meta-surfaces operating in multiband or achieving integrated functionalities.
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  • A leaky-wave antenna using double-layered metamaterial transmission line

    Xu, He-Xiu   Wang, Guang-Ming   Qi, Mei-Qing  

    A novel leaky-wave antenna (LWA) is proposed using a double-layered resonant-type metamaterial (MTM) transmission line (TL). The MTM TL is composed of periodically arranged complementary split ring resonators (CSRRs), capacitive gaps, and metal caps. By introducing the extra metal cap in additional layer of the basic artificial MTM TL element, an increased left handed capacitor by 36 % with respect to that using none cap is engineered, which is necessary to implement a balanced condition, and thus a continuous beam steering property of the resultant LWA in terms of providing phase constants from negative to positive values. For verification, a 20-cells LWA sample is fabricated and measured. Consistent numerical and experimental results have both validated the continuous frequency-scanning capabilities of the antenna from backward -29 degrees to forward 72 degrees (including the broadside). The proposed prescription opens a way toward new types of MTM LWAs with easily engineered broadside radiation.
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