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A thin-layer dielectric and metamaterial unit-cell stack loaded miniaturized SRR-based antenna for triple narrow band 4G-LTE applications
摘要： This article presents the design of a miniaturized dual-band antenna for long-term evolution (LTE) application is presented. In the basic antenna design, split ring resonator was loaded in the radiating plane of the patch and frequency of resonance was further modified with the help of E-shaped stub. The antenna has been fabricated using FR-4 substrate and the measured dual bands at 2.11 and 2.665 GHz are found in a close match with the simulated data. By placing a thin dielectric resonator of permittivity εr = 10.2 and thickness of 1.27 mm, two closely spaced narrow bands are obtained at 2.217 and 2.28 GHz. A novel metamaterial unit-cell having near-zero refractive index is designed and mounted above the dielectric resonator. This stack configuration generates triple narrow frequency band in the LTE 2 GHz spectrum range. The overall size of the proposed antenna is 20 × 25 mm2.
关键词： triple band,split ring resonator,thin layer dielectric resonator,reflection coefficient,patch,unit-cell
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Advanced Technologies for Communications (ATC) - Ho Chi Minh City, Vietnam (2018.10.18-2018.10.20)] 2018 International Conference on Advanced Technologies for Communications (ATC) - Wideband Unit-cell for Linearly Polarized X-band Transmitarray Applications
摘要： In this paper, we present a large phase range unit-cell for X-band passive transmitarray antennas. The unit-cell is designed by using the combination of cut-circular patches and cut-ring slots. A 3-bit phase resolution has been optimized to provide eight values of the transmission phase with a step of 45°. The bandwidth of -1 dB transmission magnitude reaches 21.3%. A 10x10-element transmitarray based on the unit-cell configuration has been simulated. The transmitarray antenna provides good radiation patterns and a high aperture efficiency of 52.1%.
关键词： flat lens antenna,Transmitarray,transmitarray antenna,transmitarray unit-cell
更新于2025-09-23 15:22:29
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3-3 Piezoelectric Metamaterial with Negative and Zero Poisson’s Ratio for Hydrophones Applications
摘要： This study presents the electromechanical properties of the 3-3 piezoelectric metamaterial based on variants of honeycomb (HC) structure. Three kinds of three-dimensional (3D) elastically anisotropic and piezoelectrically active HC structures were introduced, namely, conventional HC (3D-CHC), a re-entrant HC (3D-RE) and a semi-re-entrant HC (3D-SRE). Highly porous 3D finite element models of the mentioned three kinds of metamaterials were developed and the role of ligament orientation on their effective elastic, piezoelectric and dielectric properties was completely characterized. The intrinsic symmetry of HC structure was utilized and simplified mixed boundary conditions equivalent to periodic boundary conditions were recognized. In comparison to their bulk constituent, all the 3-3 type piezoelectric HC networks exhibited an enhanced response, especially for the longitudinal poling. The normalized figures of merit show a mild dependence on the angle θ and the underlying deformation mechanisms associated with the zero, positive and negative Poisson’s ratios. Figures of merit such as hydrostatic strain coefficient (hd), the hydrostatic figure of merit (ghhd) and the acoustic impedance (Z) reached their best values at small angles, i.e., θ=30°. Longitudinally poled networks exhibited four order of magnitude increase in their hydrostatic figure of merit (foam to solid ratio >10,000) and one order of magnitude decrease in the acoustic impedance indicating their applicability for the design of hydrophones.
关键词： piezoelectric materials,auxetic smart structures,metamaterials,electromechanical properties,cellular materials,honey comb structures,unit cell method
更新于2025-09-23 15:19:57
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[IEEE 2018 18th Mediterranean Microwave Symposium (MMS) - Istanbul, Turkey (2018.10.31-2018.11.2)] 2018 18th Mediterranean Microwave Symposium (MMS) - Polarization Insensitive Metamaterial Absorber Using Sunflower Shaped Unit Cell
摘要： In this paper, a novel polarization insensitive metamaterial absorber using sunflower shaped unit cell is proposed. The performance of the proposed absorber was demonstrated with 3D full-wave EM solver under normal incidence for TE and TM polarization modes. Due to the symmetric geometry of the sunflower shaped unit cell, the proposed absorber provides a high level of absorptivity, about %90, for both TE and TM modes at 11.9 GHz. To enhance the absorptivity, we then created a hollow at the center of the proposed unit cell. The later device resonates at 11.7 GHz, and provides perfect absorption for both polarization modes. Our study reveals that employing hollow type symmetrical gaps provokes the interaction of EM wave and the metamaterial, and can lead to the perfect metamaterials for X-band absorber applications.
关键词： Metamaterial,absorber,X band,unit cell,polarization insensitive
更新于2025-09-19 17:15:36
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A Convoluted Structure for Miniaturized Dual-stopband Frequency Selective Surface
摘要： A miniaturized dual-bandstop frequency selective surface (FSS) using convoluted structures is proposed in this letter. The working central frequencies of the proposed FSS are 2.66 GHz and 5GHz with -3dB bandwidths of 1.5 GHz and 1.2 GHz respectively. The side length of the unit cell is 6.88mm which is about 5.9% of the wavelength at the first working frequency. The equivalent circuit and current distributions are introduced to explain the FSS frequency performance. The effects of the geometrical parameters on the frequency response of the FSS are studied. The simulated results show that the ratio of the frequencies of the two working transmission zeros can be tuned over a wide range. A prototype of the proposed FSS is fabricated and measured. The simulation and measured results show that the working frequencies, the bandwidths of the passband and two stopbands of the the proposed FSS perform excellent stabilities under different polarizations and incidence angles. This FSS is a good candidate to isolate the wireless networks.
关键词： Frequency selective surface(FSS),Miniature unit cell,Dual-band
更新于2025-09-19 17:15:36
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Laser-Driven Semiconductor Switch as a Diagnostic Method in Terahertz Band
摘要： We present a full wave, large-signal analysis of a waveguide-embedded frequency multiplier array, solving the entire geometry using FEM EM modeling and including every nonlinear element in a Harmonic Balance simulation. The full 3D model employed provides the exact field distribution across the array, thus enabling us to account for substrate resonances, higher order mode excitation, instabilities, and diode yield. The model is compared with measurements on a 247 GHz fixed tuned 72-diode HBV tripler. In this example, higher order mode excitation was found due to the interaction between the filter and the diode array. This can only be observed using a full 3D model, which more accurately predicts the output power versus input power and frequency. Finally, the pros and cons of a full 3D model and a unit cell model for waveguide embedded multiplier arrays are discussed.
关键词： unit cell modeling,varactors,higher order modes,Frequency multipliers,spatial power combining,heterostructure barrier varactors
更新于2025-09-19 17:13:59
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[IEEE 2019 Antennas Design and Measurement International Conference (ADMInC) - St. Petersburg, Russia (2019.10.16-2019.10.18)] 2019 Antennas Design and Measurement International Conference (ADMInC) - Millimeter-wave Partially Dielectric Filled Waveguide Reflectarray Antenna
摘要： Design and characteristics of millimeter-wave waveguide reflectarray antenna are considered. A specific feature of the presented antenna is a protective plastic cover that partially fills waveguides and, thus, provides additional phase correction as well. As a result, the waveguide reflectarray antenna has the relative bandwidth of 57% and 27.6 dB peak directivity. The proposed design allows manufacturing with the cheap laser-cutting and 3D printing techniques.
关键词： reflectarray,unit cell,arrays,3D printing,waveguide
更新于2025-09-19 17:13:59
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Unit-cell design for antenna arrays efficiently matched to uni-travelling-carrier photodiodes
摘要： We present an antenna array with a backing reflector that allows one to obtain efficient matching to integrated sources or loads with low input resistance. In the infinite array limit, it is possible to describe the proposed unit-cell as an equivalent network with closed-form expressions for its different constituents. This analytic approach enables the preliminary design of arrays with improved matching efficiency for optimum power transmission/reception. The proposed solution has enabled an improved matching to a uni-travelling-carrier photodiode with a maximum improvement of 3 dB in the radiated power with respect to a 72-(cid:2) antenna, and featuring a 50% bandwidth.
关键词： uni-travelling-carrier photodiodes,radiated power,unit-cell design,impedance matching,antenna array
更新于2025-09-16 10:30:52
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Accurate Extraction of Equivalent Circuit Parameters of Spiral Resonators for the Design of Metamaterials
摘要： Spiral resonators (SRs) are one of the most common typologies of resonant magnetic unit cell for the realization of metamaterials. The precise knowledge of their lumped electric properties (RLC parameters) is of crucial importance in the metamaterial design. Thus, an accurate and unambiguous procedure for estimating the value of the RLC lumped parameters of compact SRs is introduced. The proposed procedure relies on a rigorous approach allowing a complete characterization of SRs also in terms of Q-factor. The method is general and valid for other shapes of resonators. The estimations have been finally verified by performing measurements on fabricated SRs through a magnetic probe.
关键词： spiral resonators (SRs),scattering parameters,unit cell,Metamaterial,resonant frequency
更新于2025-09-09 09:28:46
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Theoretical Analysis of Moving Reference Planes Associated with Unit Cells of Nonreciprocal Lossy Periodic Transmission-Line Structures
摘要： This paper presents a theoretical analysis of moving reference planes associated with unit cells of non-reciprocal lossy periodic transmission-line structures (NRLSPTLSs) by the equivalent bi-characteristic-impedance transmission line (BCITL) model. Applying the BCITL theory, only the equivalent BCITL parameters (characteristic impedances for waves propagating in forward and reverse directions and associated complex propagation constants) are of interest. An infinite NRLSPTLS is considered first by shifting a reference position of unit cells along TLs of interest. Then, a semi-infinite terminated NRLSPTLS is investigated in terms of associated load reflection coefficients. It is found that the equivalent BCITL characteristic impedances of the original and shifted unit cells are mathematically related by the bilinear transformation. In addition, the associated load reflection coefficients of both unit cells are mathematically related by the bilinear transformation. However, the equivalent BCITL complex propagation constants remain unchanged. Numerical results are provided to show the validity of the proposed theoretical analysis.
关键词： bilinear transformation,Unit cell,periodic transmission-line structure,bi-characteristic-impedance transmission line (BCITL)
更新于2025-09-09 09:28:46