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Search results for: DIRECTIVE ANTENNAS
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Computationally Efficient Surrogate-Assisted Design of Pyramidal-Shaped 3D Reflectarray Antennas
PublicationReflectarrays (RAs) have been attracting considerable interest in the recent years due to their appealing features, in particular, a possibility of realizing pencil-beam radiation patterns, as in the phased arrays, but without the necessity of incorporating the feeding networks. These characteristics make them attractive solutions, among others, for satellite communications or mobile radar antennas. Notwithstanding, available microstrip...
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Multi-Criterial Design of Antennas with Tolerance Analysis Using Response-Feature Predictors
PublicationImperfect manufacturing is one of the factors affecting the performance of antenna systems. It is particularly important when design specifications are strict and leave a minimum leeway for a degradation caused by geometry or material parameter deviations from their nominal values. At the same time, conventional antenna design procedures routinely neglect to take the fabrication tolerances into account, which is mainly a result...
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Overview of Metamaterials-Integrated Antennas for Beam Manipulation Applications: The Two Decades of Progress
PublicationMetamaterials (MMs) are synthetic composite structures with superior properties not found in naturally occurring materials. MMs have gained massive attention over the last two decades because of their extraordinary properties, such as negative permittivity and permeability. These materials enable many applications in communication subsystems, especially in the field of antenna design, to enhance gain, bandwidth, and efficiency,...
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Rapid redesign of multiband antennas with respect to operating conditions and material parameters of substrate
PublicationThis work addresses geometry parameter scaling of multi-band antennas for Internet of Things applications. The presented approach is comprehensive and permits re-design of the structure with respect to both the operating frequencies and material parameters of the dielectric substrate. A two-step procedure is developed with the initial design obtained from an inverse surrogate model constructed using a set of appropriately prepared...
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Expedited simulation-driven design optimization of UWB antennas by means of response features
PublicationIn this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature-based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions...
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Effects of different defective linkers on the photocatalytic properties of Cu-BTC for overall water decomposition
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Accelerated Monte Carlo method for computation of photon migration by matrix description of photon direction
PublicationPrzedstawiono metodę obliczeń dyfuzji fotonów w materiałach silnie rozpraszających, będącą modyfikacją metody Monte Carlo. Modyfikacja ta polega na zastąpieniu wektorowego opisu kierunku propagacji fotonów poprzez opis macierzowy, co pozwala na około 5% redukcję czasu obliczeń na komputerach z jednopotokowym przetwarzaniem zmiennopozycyjnym lub większą w wypadku wielopotokowego przetwarzania.
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Contribution of Strength, Speed and Power Characteristics to Change of Direction Performance in Male Basketball Players
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Proposals of Frequency-Based and Direction Methods to Reduce the Influence of Surface Topography Measurement Errors
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Parasites of the digestive tract of sheep and goats from organic farms in Western Pomerania, Poland
PublicationThe aim of the study was to determine the prevalence and intensity of parasite infection of the digestive tract in sheep and goats from the West Pomerania region following anti-parasite treatment. Feces were freely collected from sheep and goats kept on organic farms and subjected to analysis by the Willis-Schlaf and McMaster’s flotation methods. The mean extensity of infection by gastrointestinal parasites...
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Stress anisotropy characterisation with the help of Barkhausen effect detector with adjustable magnetic field direction
PublicationIn the paper we describe a novel apparatus for the measurement of the Barkhausen noise (BN) angular dependence, which in turn may be indicative of the stress induced anisotropy of magnetic properties. Such dependence can be further used for the stress distribution evaluation. The change of magnetization direction in the material is obtained by varying the magnetic flux density in two perpendicular yokes of the apparatus. We present...
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Cutting forces related to the direction of primary motion during machining on frame sawing machines.
PublicationW pracy przedstawiono efekty energetyczne przecinania drewna na pilarce ramowej za pomocą cienkich pił. Podano podstawy teoretyczne oraz wyniki badań doświadczalnych sił skrawania działających na kierunku ruchu głównego ( siły skrawania określano podczas podawania przecinanego materiału oraz w czasie gdy prędkość posuwu wynosiła 0).
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Measurements of differential cross sections for elastic electron scattering in the backward direction by molecular oxygen.
PublicationZmierzono różniczkowe przekroje czynne na rozproszenie sprężyste elektronów na cząsteczkach tlenu w zakresie kątów rozproszenia 100-180 st., dla wybranych energii padających elektronów w przedziale 7-20eV. Do pomiarów wykorzystano metodę lokalnego pola magnetycznego.
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A new method for searching optimal path on a raster plane including cost of direction changes
PublicationArtykuł przedstawia nowy algorytm znajdowania optymalnych tras na siatkach rastrowych. Szczegółowo opisano zastosowane struktury danych, dzięki który algorytm ma liniową złoŻoność obliczeniową. Zamieszczono również propozycje możliwych zastosowań.
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Design of UWB coplanar antenna with reduced ground plane
PublicationW artykule przedstawiono projekt kompaktowej anteny szerokopasmowej złożonej z dwóch kołowych pasków koplanarnych ograniczających szczelinę o podobnym kształcie. Antena zasilona była z 50 Ω linii trójpaskowej. Przeprowadzono badania wpływu zewnętrznego paska na pasmo anteny. Zaprojektowana antena została zbadana eksperymentalnie pokazując bardzo dobre parametry: w paśmie 1.7-15.5GHz uzyskano |S11| < −10dB. Antena charakteryzowała...
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Double-ridged horn antenna with sinusoidal ridge profile
PublicationPrzedstawiono wyniki symulacji numerycznej oraz pomiarów parametrów anteny tubowej z podwójnym grzbietem. Badania numeryczne dotyczyły zarówno samego układu zasilania falowodu grzbietowego jak i całej anteny z uwzględnieniem sinusoidalnego profilu impedancji grzbietu. Wyniki obliczeń dopasowania oraz charakterystyk promieniowania, wykonanych przy użyciu symulatora QW-3D, porównano z wynikami pomiarów, stwierdzając dobrą zgodność...
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Broadband Microstrip Patch Antenna with Reduced Transversal Size
PublicationW pracy przedstawiono propozycję anteny szerokopasmowej o ograniczonych wymiarach poprzecznych. Szerokopasmowość uzyskano poprzez stosowanie grubego podłoża i sprzężenia elektromagnetycznego poprzez dwie szczeliny sprzęgające. Wymiar poprzeczny łaty zredukowano poprzez zastosowanie szczeliny typu H. Antena została zaprojektowana i wykonana, zaś zmierzone pasmo wyniosło 29% dla WFS <1.5. Stwierdzono jednak, że charakterystyki...
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Inexpensive Helical Antenna for Global Navigation Satellite Systems
PublicationZaprezentowane zostały wyniki badań teoretycznych oraz eksperymentalnych niskobudżetowej anteny na pasmo L. Wyjściowa geometria struktury została obliczona na podstawie ogólnych wzorów. Efekt przesunięcia częstotliwości wywołany przez użycie rdzenia PU został również uwzględniony. Równolegle przeprowadzono badania wrażliwości parametrów anteny na proces produkcji. Zaprojektowano i wykonano układ dopasowania impedancyjnego. W paśmie...
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Diagnostics of thermal processes in antenna systems of broadcast stations
PublicationDiagnostics is an important element associated with the operation of a radio antenna systems, allowing earlier detection of potential damage. Thermography is one of the diagnostic tools, which allows for non-invasive assessment of technical condition. It brings together both financial savings associated with the removal of the damage and the potential effects caused by it. The article presents an example of using a thermal imaging...
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Small Antenna Design Using Surrogate-Based Optimization
PublicationIn this work, design of small antennas using efficient numerical optimization is investigated. We exploit variable-fidelity electromagnetic (EM) simulations and the adaptively adjusted design specifications (AADS) technique. Combination of these methods allows us to simultaneously adjust multiple geometry parameters of the antenna structure of interest in a computationally feasible manner, leading to substantial reduction of the...
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A structure and design of a novel compact UWB MIMO antenna
PublicationIn the paper, a concept and design procedure of a novel compact MIMO slot antenna is presented. In order to achieve a better filling of available space, individual antennas are constrained to a triangular shape and optimized for a reduced size. The MIMO structure is then assembled using the two of previously designed antennas in orthogonal arrangement. Surrogate-assisted numerical optimization involving variable-fidelity electromagnetic...
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Novel structure and design of compact UWB slot antenna
PublicationIn this paper, a novel structure of a compact UWB slot antenna is presented along with a simulation-driven design optimization algorithm for adjusting geometry parameters of the device. Our primary objective is to obtain small footprint of the structure while maintaining its acceptable electrical performance. It is achieved by introducing sufficiently large number of geometry degrees of freedom, including increased number of parameterized...
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Single-Anchor Indoor Localization Using ESPAR Antenna
PublicationIn this paper a new single-anchor indoor localization concept employing Electronically Steerable Parasitic Array Radiator (ESPAR) antenna has been proposed. The new concept uses a simple fingerprinting algorithm adopted to work with directional main beam and narrow minimum radiation patterns of ESPAR antenna that scans 360° area around the base station, while the signal strength received from a mobile terminal is being recorded...
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Design optimization of novel compact circular polarization antenna
PublicationThe paper describes a structure and a design optimization procedure of a miniaturized circular polarization antenna with elliptical ground plane slots and feed line with stepped-impedance stubs. Constrained optimization of all antenna parameters is executed in order to explicitly reduce the antenna size while maintaining required impedance axial ratio bandwidth of 5 GHz to 7 GHz at the same time. The size of the optimized antenna...
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Compact antenna array comprising fractal-shaped microstripradiators
PublicationA design method of antenna array consisting of eight microstrip patches modified with Sierpinski fractal curves has been presented andexperimentally validated in this paper. Method proposed has enabled the achievement of considerable miniaturization of array length (26%),together with multi-band behavior of the antenna, which proves the attractiveness of presented design methodology and its ability to be implemented in more complex...
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Knowledge-based performance-driven modeling of antenna structures
PublicationThe importance of surrogate modeling techniques in the design of modern antenna systems has been continuously growing over the recent years. This phenomenon is a matter of practical necessity rather than simply a fashion. On the one hand, antenna design procedures rely on full-wave electromagnetic (EM) simulation tools. On the other hand, the computational costs incurred by repetitive EM analyses involved in solving common tasks...
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A Geometrically Simple Compact Wideband Circularly Polarized Antenna
PublicationA compact broadband wide-slot circular polarization (CP) antenna is proposed. An inverted L-shape parasitic strip at the open end of a microstrip line extension and a slot modification is applied to attain wideband CP. The advantage of this technique is simplicity which makes it readily re-designable for different frequency bands. To demonstrate the concept, three designs working at different frequencies are obtained. The redesign...
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Compact CPW-fed Sierpinski fractal monopole antenna.
PublicationZaproponowano nową wielozakresową strukturę antenową dla zastosowań wielosystemowych. Jest to zminiaturyzowana antena monopolowa planarna, której obwód zaprojektowano wykorzystując czwartego rzędu iterację trójkąta Sierpińskiego ze współczynnikiem skali d=1.5. Antenę wykonano na podłożu dielektrycznym i zasilono wykorzystując falowód koplanarny. Badania parametrów wykonanego modelu potwierdziły wielozakresową pracę struktury.
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Katarzyna Wojan dr hab.
PeopleDr habil., assiociate professor, Polish linguist, lexicographer, bibliographer; Finnish, Russian, Slavonic languages; confrontative linguistics, lexicology, lexicography, history of Polish lexicography, translation studies, intercultural communication, reception of Polish literature abroad, translations Editor-in-Chief of the Journal "Studia Rossica Gedanensia" (annual)
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Design space reduction and variable-fidelity EM simulations for feasible Pareto optimization of antennas
PublicationA computationally efficient procedure for multi-objective optimization of antenna structures is presented. In our approach, a response surface approximation (RSA) model created from sampled coarse-discretization EM antenna simulations is utilized to yield an initial set of Pareto-optimal designs using a multi-objective evolutionary algorithm. The final Pareto front representation for the high-fidelity model is obtained using surrogate-based...
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An Analysis of Probe-Fed Rectangular Patch Antennas With Multilayer and Multipatch Configurations on Cylindrical Surfaces
PublicationA multi-patch configuration of probe-fed rectangular microstrip antennas mounted on a cylindrical body, with electrically small radius, with an arbitrary number of substrate and superstrate layers is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. A unified procedure for creating proper matrices for the investigated geometry of the structure is outlined here. Numerical results for...
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Rapid design optimization of antennas using variable-fidelity EM models and adjoint sensitivities
PublicationPurpose – Development of techniques for expedited design optimization of complex and numerically expensive electromagnetic (EM) simulation models of antenna structures validated both numerically and experimentally. The paper aims to discuss these issues. Design/methodology/approach – The optimization task is performed using a technique that combines gradient search with adjoint sensitivities, trust region framework, as well as...
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Cost-efficient multi-objective design optimization of antennas in highly-dimensional parameter spaces
PublicationMulti-objective optimization of antenna structures in highly-dimensional parameter spaces is investigated. For expedited design, variable-fidelity EM simulations and domain patching algorithm are utilized. The results obtained for a monopole antenna with 13 geometry parameters are compared with surrogate-assisted optimization involving response surface approximation modeling.
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EM‐driven constrained miniaturization of antennas using adaptive in‐band reflection acceptance threshold
PublicationNumerical optimization of geometry parameters is a critical stage of the design process of compact antennas. It is also challenging because size reduction is constrained by the necessity of fulfilling imposed electrical performance requirements. Furthermore, full‐wave electromagnetic (EM) analysis needs to be used for reliable performance evaluation of the antenna structure, which is computationally expensive. In this paper, an...
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Constrained optimization for generating gain-bandwidth design trade-offs of wideband unidirectional antennas
PublicationBroadband unidirectional antennas realised in microstrip technology find applications in many wireless communication systems. One of their design challenges is the necessity of handling multiple performance figures which is difficult when using traditional design methods, largely based on parameter sweeping. This work presents a simple optimisation-based framework that permits generation of gain-bandwidth trade-off designs for...
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Reduced-cost design closure of antennas by means of gradient search with restricted sensitivity update
PublicationDesign closure, i.e., adjustment of geometry parameters to boost the performance, is a challenging stage of antenna design process. Given complexity of contemporary structures, reliable parameter tuning requires numerical optimization and can be executed using local algorithms. Yet, EM-driven optimization is a computationally expensive endeavour and reducing its cost is highly desirable. In this paper, a modification of the trust-region...
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A design framework for rigorous constrained EM-driven optimization of miniaturized antennas with circular polarization
PublicationCompact radiators with circular polarization are important components of modern mobile communication systems. Their design is a challenging process which requires maintaining simultaneous control over several performance figures but also the structure size. In this work, a novel design framework for multi-stage constrained miniaturization of antennas with circular polarization is presented. The method involves sequential optimization...
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Expedited Design Closure of Antennas By Means Of Trust-Region-Based Adaptive Response Scaling
PublicationIn the letter, a reliable procedure for expedited design optimization of antenna structures by means of trust-region adaptive response scaling (TR-ARS) is proposed. The presented approach exploits two-level electromagnetic (EM) simulation models. A predicted high-fidelity model response is obtained by applying nonlinear frequency and amplitude correction to the low-fidelity model. The surrogate created this way is iteratively rebuilt...
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Domain segmentation for low-cost surrogate-assisted multi-objective design optimisation of antennas
PublicationAbstract: Information regarding the best possible design trade-offs of an antenna structure can be obtained through multiobjective optimisation (MO). Unfortunately, MO is extremely challenging if full-wave electromagnetic (EM) simulation models are used for performance evaluation. Yet, for the majority of contemporary antennas, EM analysis is the only tool that ensures reliability. This study introduces a procedure for accelerated...
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Statistical analysis and robust design of circularly polarized antennas using sequential approximate optimization
PublicationIn the paper, reliable yield estimation and tolerance-aware design optimization of circular polarization (CP) antennas is discussed. We exploit auxiliary kriging interpolation models established in the vicinity of the nominal design in order to speed up the process of statistical analysis of the antenna structure at hand. Sequential approximate optimization is then applied to carry out robust design of the antenna, here, oriented...
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Expedited Trust-Region-Based Design Closure of Antennas by Variable-Resolution EM Simulations
PublicationThe observed growth in the complexity of modern antenna topologies fostered a widespread employment of numerical optimization methods as the primary tools for final adjustment of the system parameters. This is mainly caused by insufficiency of traditional design closure approaches, largely based on parameter sweeping. Reliable evaluation of complex antenna structures requires full-wave electromagnetic (EM) analysis. Yet, EM-driven...
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Tolerance-Aware Multi-Objective Optimization of Antennas by Means of Feature-Based Regression Surrogates
PublicationAssessing the immunity of antenna design to fabrication tolerances is an important consideration, especially when the manufacturing process has not been predetermined. At the same time, the antenna parameter tuning should be oriented toward improving the performance figures pertinent to both electrical (e.g., input matching) and field properties (e.g., axial ratio bandwidth) as much as possible. Identification of available trade-offs...
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A framework for accelerated optimization of antennas using design database and initial parameter set estimation
PublicationThe purpose of this paper is to exploit a database of pre-existing designs to accelerate parametric optimization of antenna structures is investigated. Design/methodology/approach The usefulness of pre-existing designs for rapid design of antennas is investigated. The proposed approach exploits the database existing antenna base designs to determine a good starting point for structure optimization and its response sensitivities....
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Expedited Yield Optimization of Narrow- and Multi-Band Antennas Using Performance-Driven Surrogates
PublicationUncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to...
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Nested Kriging with Variable Domain Thickness for Rapid Surrogate Modeling and Design Optimization of Antennas
PublicationDesign of modern antennas faces numerous difficulties, partially rooted in stringent specifications imposed on both electrical and field characteristics, demands concerning various functionalities (circular polarization, pattern diversity, band-notch operation), but also constraints imposed upon the physical size of the radiators. Conducting the design process at the level of full-wave electromagnetic (EM) simulations, otherwise...
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In vitro characteristics ofLactobacillusspp. strains isolated from the chicken digestive tract and their role in the inhibition ofCampylobactercolonization
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A Comprehensive Survey on Antennas On-Chip Based on Metamaterial, Metasurface, and Substrate Integrated Waveguide Principles for Millimeter-Waves and Terahertz Integrated Circuits and Systems
PublicationAntennas on-chip are a particular type of radiating elements valued for their small footprint. They are most commonly integrated in circuit boards to electromagnetically interface free space, which is necessary for wireless communications. Antennas on-chip radiate and receive electromagnetic (EM) energy as any conventional antennas, but what distinguishes them is their miniaturized size. This means they can be integrated inside...
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RSS-Based DoA Estimation Using ESPAR Antenna Radiation Patterns Spline Interpolation
PublicationIn this paper, it is shown how power pattern crosscorrelation (PPCC) algorithm, which relies on received signal strength (RSS) values recorded at electronically steerable parasitic array radiator (ESPAR) antenna output port, used for direction-of-arrival (DoA) estimation, can easily be improved by applying spline interpolation to radiation patterns recorded in the calibration phase of the DoA estimation process. The proposed method...
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Simple Superstrate Antenna for Connectivity Improvement in Precision Farming Applications
PublicationIn this paper, a concept of a simple circularly polarized antenna with partially reflecting surface (PRS) has been adopted for precision farming applications. The investigation contains an analysis of the dependence of the antenna performance on the elements number in the PRS structure in X- and Ka-band frequencies. Especially meaningful parameters from point-to-point connectivity perspective are...
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Influence of realistic antenna radiation pattern on rf fingerprinting accuracy
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