Bio: Xing Chen is an academic researcher from Sichuan University. The author has contributed to research in topics: Antenna (radio) & Dipole antenna. The author has an hindex of 13, co-authored 44 publications receiving 384 citations.
TL;DR: In this paper, a planar slot array antenna with omnidirectional radiation pattern in the horizontal plane is proposed, which employs a low-cost and accurate planar printed technique.
Abstract: A novel planar slot array antenna with omnidirectional radiation pattern in the horizontal plane is proposed. The antenna has a simple structure based on a stripline. Its fabrication employs a low-cost and accurate planar printed technique. A series of rectangular-shaped loop slots are etched on two parallel ground planes, and act as radiators. The basic principle of operation of the antenna is discussed in this study. An antenna with eight back-to-back slots is designed by employing the genetic algorithm (GA) implemented on a cluster system to achieve good omnidirectional radiation characteristics. A prototype antenna is fabricated and measured. The measurement results agree with the simulation data and show that this antenna possesses encouraging features. For example, at the working frequency of 5.8 GHz, it has a well-formed omnidirectional pattern with maximum gain variation less than 0.5 dB in the horizontal plane, a high gain level of 10 dBi, side lobes 10 dB below the main lobe and no beam squint. Meanwhile, this antenna achieves an impedance bandwidth of 4.6% of the center frequency (5.68-5.95 GHz) for S11 <; -10 dB and exhibits stable omnidirectional performance over the impedance bandwidth.
TL;DR: In this paper, an electrically tunable metasurface that absorbs continuous electromagnetic (EM) surface waves is proposed by taking advantage of varactor diodes embedded in the surface.
Abstract: An electrically tunable metasurface that absorbs continuous electromagnetic (EM) surface waves is proposed by taking advantage of varactor diodes embedded in the surface. On the one hand, the varactors perform as the main dissipating components due to their parasitic series resistance; on the other hand, they function as the tuning elements because the dissipation is highly dependent on their capacitance. Therefore, the absorption of the surface can be tuned by the direct current biasing voltage across the varactors, which is validated numerically and experimentally in this letter. This absorbing mechanism of the surface differs from prior surface-wave absorbers and can lead to greater flexibility for absorbing metasurfaces. In this work, a power-dependent absorbing performance is achieved by loading microwave power sensors. If incorporated with other types of sensors, the absorption could potentially be controlled by corresponding physical variables such as light, pressure, or temperature, thus giving rise to various absorbing applications in a complex EM environment.
TL;DR: In this paper, the authors proposed a power-dependent impedance surface, which consists of a lattice of modified slotted mushroom-like cells loaded with varactor diodes and lumped circuits.
Abstract: Impedance surfaces are artificially designed periodic structures that support surface waves. This paper presents a novel concept of a nonlinear impedance surface, whose impedance increases with the surface wave power. The proposed surface consists of a lattice of modified slotted mushroom-like cells loaded with varactor diodes and lumped circuits. The circuits are designed to sense the incoming surface wave power and feed back the signal to control the bias of the varactors, which eventually tunes the surface impedance. Such proposed power-dependent impedance surface has been demonstrated by a prototype consisting of $4 \times 10$ cells. It is observed from the experiments that as the power varies from 16 to 27 dBm, the surface exhibits a surface impedance range as much as j385 to j710 $\Omega$ . This characteristic enables the surface to be potentially useful in self-trapping surface-wave waveguide, power-dependent beam-steering antenna reflector, and other nonlinear applications.
TL;DR: In this paper, a wideband and compact microstrip grid array antenna is presented, which adopts elliptical radiation elements to enhance its impedance and gain bandwidths, and sinusoid lines to reduce its size.
Abstract: A wideband and compact microstrip grid array antenna is presented. The antenna is printed on a dielectric substrate, backed by a metal board, and directly fed from a 50 ? coaxial cable. It adopts elliptical radiation elements to enhance its impedance and gain bandwidths, and sinusoid lines to reduce its size. Structural parameters of a proposed antenna with 7 radiation elements were optimized by a parallel genetic algorithm (GA) on a cluster system. A prototype antenna was fabricated and tested. Results of simulation and measurement agree well and show the antenna exhibits encouraging properties, e.g., S11 < -10 dB bandwidth of 25% and a 3 dB gain-drop bandwidth of 16.3%, both of which are much wider than that of conventional grid array antennas, as well as a maximum gain of approximately 13.7 dBi with an area-reduction factor of 47%.
TL;DR: In this article, a novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented, which is fabricated on a three-layer printed circuit board, which comprises an array of periodic metammaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes.
Abstract: A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a ha...
01 Nov 1984
TL;DR: In this article, a substrate-superstrate printed antenna geometry which allows for large antenna gain is presented, asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed.
Abstract: Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.
TL;DR: In this article, a review of the recent developments in dielectric structures for shaping optical wavefronts is presented with an outlook on future potentials and challenges that need to be overcome.
Abstract: During the past few years, metasurfaces have been used to demonstrate optical elements and systems with capabilities that surpass those of conventional diffractive optics. Here, we review some of these recent developments, with a focus on dielectric structures for shaping optical wavefronts. We discuss the mechanisms for achieving steep phase gradients with high efficiency, simultaneous polarization and phase control, controlling the chromatic dispersion, and controlling the angular response. Then, we review applications in imaging, conformal optics, tunable devices, and optical systems. We conclude with an outlook on future potentials and challenges that need to be overcome.
TL;DR: Metasurfaces have been a topic of significant research and are used in various applications due to their unique ability to manipulate electromagnetic waves in microwave and optical frequencies as mentioned in this paper, which has the advantages of light weight, ease of fabrication, and ability to control wave propagation both on the surface and in the surrounding free space.
Abstract: Metasurfaces are a topic of significant research and are used in various applications due to their unique ability to manipulate electromagnetic waves in microwave and optical frequencies. These artificial sheet materials, which are usually composed of metallic patches or dielectric etchings in planar or multi-layer configurations with subwavelength thickness, have the advantages of light weight, ease of fabrication, and ability to control wave propagation both on the surface and in the surrounding free space. Recent progress in the field has been classified by application and reviewed in this article. Starting with the development of frequency-selective surfaces and metamaterials, the unique capabilities of different kinds of metasurfaces have been highlighted. Surface impedance can be varied and manipulated by patterning the metasurface unit cells, which has broad applications in surface wave absorbers and surface waveguides. They also enable beam shaping in both transmission and reflection. Another important application is to radiate in a leaky wave mode as an antenna. Other applications of metasurfaces include cloaking, polarizers, and modulators. The controllable surface refractive index provided by metasurfaces can also be applied to lenses. When active and non-linear components are added to traditional metasurfaces, exceptional tunability and switching ability are enabled. Finally, metasurfaces allow applications in new forms of imaging.
Royal Institute of Technology1, Zhejiang University2, Aalto University3, University of Michigan4, University of Siena5, University of Toronto6, Nanyang Technological University7, University of Southampton8, Purdue University9, University of California, San Diego10, École Polytechnique de Montréal11, City University of New York12, Fudan University13, University of Paris14, Carlos III Health Institute15, University of Zagreb16, University of Seville17, Université catholique de Louvain18
TL;DR: Metasurfaces are thin two-dimensional metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions as discussed by the authors, and have been demonstrated to be able to p...
Abstract: Metasurfaces are thin two-dimensional metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions. For example, metasurfaces have been demonstrated to p ...
TL;DR: A new research direction of software‐defined metAsurfaces is described, which attempts to push metasurfaces toward unprecedented levels of functionality by harnessing the opportunities offered by their software interface as well as their inter‐ and intranetwork connectivity and establish them in real‐world applications.
Abstract: This work was supported by the European Union’s Horizon 2020 research and innovation programme-Future Emerging Topics (FETOPEN) under grant agreement No 736876 (VISORSURF). Financial support by the National Priorities Research Program grant No. NPRP9-383-1-083 from the Qatar National Research Fund is also acknowledged. O.T. acknowledges the ﬁnancial support of the Stavros Niarchos Foundation within the framework of the project ARCHERS (“Advancing Young Researchers’ Human Capital in Cutting Edge Technologies in the Preservation of Cultural Heritage and the Tackling of Societal Challenges”).