Search results for: NARROW-BAND ANTENNAS
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PbGa2GeS6 crystal as a novel nonlinear optical material: Band structure aspects
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Miniaturized uniplanar triple-band slot dipole antenna with folded radiator
PublicationA miniaturized uniplanar slot dipole for triple-frequency operation is presented. The antenna consists of a folded slot radiator with an increased number of degrees of freedom that allow for efficient size reduction. Rigorous electromagnetic (EM)-driven design optimization is applied in order to achieve the smallest possible size while maintaining acceptable levels of antenna reflection at the required operating frequencies. The...
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Low temperature broad band dielectric spectroscopy of multiferroic Bi6Fe2Ti3O18 ceramics
PublicationIn the present research the tool of broadband dielectric spectroscopy was utilized to characterize dielectric behavior of Bi6Fe2Ti3O18 (BFTO) Aurivillius-type multiferroic ceramics. Dielectric response of BFTO ceramics was studied in the frequency domain (Δν=0.1Hz – 10MHz) within the temperature range ΔT=-100°C – 200°C. The Kramers-Kronig data validation test was employed to validate the impedance data measurements and it was found...
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Shear band evolution phenomena in direct shear test modelled with DEM.
PublicationA direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear...
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The optical properties and band gap energy of nanocrystalline La0.4Sr0.6TiO3 thin films
PublicationW pracy zbadano wpływ mikrostruktury na właściwości optyczne La0.4Sr0.6TiO3 przygotowanego w postaci cienkiego filmu. Gęsty film o grubości 200nm i wielkości krystalitów 14-30nm został przygotowany na szafirze.
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The forecasted values of cutting power for sawing on band sawing machines for Polish Scots pine wood (Pinus sylvestris L.) in a function of its provenance.
PublicationIn this paper the predicted values of cutting power for band sawing machine (EB 1800, f. EWD), which is used in the Polish sawmills, were showed. The values of cutting power were forecasted for Scots pine (Pinus sylvestris L.) wood of five provenances from Poland. These values were determined using an innovative method of predicting the cutting power, which takes into account of elements of fracture mechanics. The resulting predictions...
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Precise Evaluation of Gas–Liquid Two-Phase Flow Pattern in a Narrow Rectangular Channel with Stereology Method
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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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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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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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EM-Driven Size Reduction and Multi-Criterial Optimization of Broadband Circularly-Polarized Antennas Using Pareto Front Traversing and Design Extrapolation
PublicationMaintaining small size has become an important consideration in the design of contemporary antenna structures. In the case of broadband circularly polarized (CP) antennas, miniaturization is a challenging process due to the necessity of simultaneous handling of electrical and field properties (reflection, axial ratio, gain), as well as ensuring sufficient frequency range of operation, especially at the lower edge of the antenna...
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Expedited Re-Design of Multi-Band Passive Microwave Circuits Using Orthogonal Scaling Directions and Gradient-Based Tuning
PublicationGeometry scaling of microwave circuits is an essential but challenging task. In particular, the employment of a given passive structure in a different application area often requires re-adjustment of the operating frequencies/bands while maintaining top performance. Achieving this necessitates utilization of numerical optimization methods. Nonetheless, if the intended frequencies are distant from the ones at the starting point,...
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Designing a high-sensitivity dual-band nano-biosensor based on petahertz MTMs to provide a perfect absorber for early-stage non-melanoma skin cancer diagnostic
PublicationThe purpose of this study is development of a novel high-performance low-Petahertz (PHz) biosensor for non-melanoma skin cancer (NMSC) diagnosis. The presented device is designed to work within a microwave imaging regime, which is a promising alternative to conventional diagnostic methods such as visual examination, dermoscopy, and biopsy. The suggested biosensor incorporates a dual-band perfect absorber (operating bands at 0.909...
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Effective one-band Hamiltonian for the copper-oxygen plane in the superconducting copper oxides
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Electronic and optical properties of theMg2−xFexSiO4spinel: From band insulator to Mott insulator
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Dipolowe anteny planarne do zastosowań w standardzie Ultra-Wide band
PublicationW pracy dokonano przeglądu dipolowych anten planarnych projektowanych dla standardu UWB. Przedstawiono przykładowe promienniki oraz symetryzatory szerokopasmowe, które składają sie na antenę dipolową. porównano dopasowania anten dla wybranych kształtów promienników.
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Design of compact self-quintuplexing antenna with high-isolation for penta-band applications
PublicationThis article presents a novel compact self-quintuplexing antenna architecture based on a substrate-integrated rectangular cavity (SIRC) for pentaband applications. The proposed self-quintuplexing antenna is constructed by employing an SIRC, one Pi-shaped slot (PSS), one T-shaped slot (TSS), and five 50Ω microstrip feedlines. The PSS and TSS are engraved on the top of the SIRC to create five radiating patches, which are excited...
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The Righi-Leduc effect: on evidence of two-band electronic structure in Nd1.86Ce0.14CuO4-y.
PublicationPrzedstawiono badania temperaturowe zależności oporu elektrycznego, efektu Halla (RH), przewodnictwa cieplnego (k) i współczynnika Righi-Leduc(SRL). Badania wykazały, że współczynnik RL> 0 w szerokim zakresie temperatur RH zmienia znak dwukrotnie w T=50 i 250K. Niezgodność znaków SRL i RH jednoznacznie wskazuje obecność w materiale nośników obu znaków tzn. n- i p- typu. W pracy pokazano, że transport ciepła zdominowany jest przez...
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Application of Dispersive Liquid-Liquid Microextraction in Narrow-Bore Tube for Preconcentration and Spectrophotometric Determination of Cadmium in Aqueous Samples
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Legal and economic identification and assessment of pharmacy substitution in narrow therapeutic index drugs, on the example of epileptic medications in Poland
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A system for Direction-Of-Arrival estimation in ISM 2.4 GHz frequency band based on ESPAR antenna and SDR technology
PublicationDetermination of the direction of the signal arrival (DOA) finds many applications in various areas of science and industry. Knowledge of DOA is used, among others to determine the position of a satellite with a low Earth orbit (LEO), localization of people and things as well as in research of wireless communication systems, for instance the determination of the number of...
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Modified monopole ring antennas as a solution for HiperLAN1/2 and IEEE 802.11b/g standard devices
PublicationZaprojektowano, wykonano i przebadano pierścieniową antenę planarną przeznaczona do aplikacji multisystemowych. Zastosowano system zasilania poprzez linie mikropaskową oraz dobrano wymiary i kształty pierścieni (promienników) w taki sposób, aby odpowiednio ''ulokować'' podzakresy pracy anteny. Zrealizowany prototyp anteny pracuje w zakresie standardów IEEE 802.11b/g oraz HiperLAN1/2.
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Mutual Coupling Between IFF/SSR Microstrip Antennas with Reduced Transversal Size- Experimental Study
PublicationW artykule opisano wyniki symulacji oraz pomiarów sprzężeń wzajemnych anten systemu IFF. Wyniki poprzedza analiza konfiguracji i działania pojedynczej anteny zasilanej szczeliną typu H. Badania przeprowadzono dla szyku poziomego i pionowego, w zakresie wejściowego współczynnika odbicia oraz współczynnika sprzężenia na dwóch częstotliwościach pasma IFF.
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Low-Cost Multi-Objective Optimization of Antennas By Means Of Generalized Pareto Ranking Bisection Algorithm
PublicationThis paper introduces a generalized Pareto ranking bisection algorithm for low-cost multi-objective design optimization of antenna structures. The algorithm allows for identifying a set of Pareto optimal sets of parameters (that represent the best trade-offs between considered objectives) by iterative partitioning of the intervals connecting previously found designs and executing a Pareto-ranking-based poll search. The initial...
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Efficient RSS-Based DoA Estimation for ESPAR Antennas Using Multiplane SDR Calibration Approach
PublicationIn this paper, we have introduced a new method to improve overall efficiency of direction-of-arrival (DoA) estimation scheme relying on received signal strength (RSS) values measured at the output port of electronically steerable parasitic array radiator (ESPAR) antenna. The proposed approach uses software-defined radio (SDR) setup and power pattern cross-correlation (PPCC) estimator involving multiple calibration planes. By placing...
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Compact Electromagnetic Lens Antennas Using Cascaded Metasurfaces for Gain Enhancement and Beam Steering Applications
PublicationElectromagnetic (EM) lens antenna designs using cascaded metasurfaces for gain enhancement and beam steering applications are proposed. Two different lens aperture designs are proposed and populated with aperiodic unit cells of size 0.2λo × 0.2λo. In lens Design 1, the unit cells of different phases are distributed in concentric circular zones, whereas in lens Design 2, the unit cells of different phases are distributed in vertical...
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Opportunistic tri-band carrier aggregation in licensed spectrum for multi-operator 5G hetnet
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4x4 Butler matrix in microstrip-slot technology for 5.4 - 5.7 GHz frequency band
PublicationW pracy zaprezentowano projekt, realizację oraz wyniki pomiarów parametrów 8-wrotowej, mikropaskowej matrycy Butlera wykonanej w technice wielowarstwowej. Poprzez odpowiednie rozmieszczenie wrót układu oraz zastosowanie sprzęgaczy wykorzystujących efekt sprzężenia poprzez szczelinę w płaszczyźnie wspólnej masy wyeliminowano konieczność zastosowania skrzyżowań linii mikropaskowych. Zrealizowany układ wydaje się obiecujący, ze względu...
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Wide-band modulation and adaptive equalization techniques for fast and reliable underwater data transmission.
PublicationSzybkość transmisji w płytkim kanale podwodnym jest ograniczona ze względu na wielokrotne odbicia fal dźwiękowych oraz niestacjonarność kanału. Dla zapewnienia szybkiej i niezawodnej transmisji danych w systemach komunikacji stosowane są złożone techniki modulacji oraz equalizacji kanału. W artykule zaproponowano zastosowanie modulacji OFDM oraz equalizacji adaptacyjnej w systemie komunikacji podwodnej. Modulacja OFDM stosowana...
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IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION
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Multi-instrument analysis of L-band amplitude scintillation observed over the Eastern Arabian Peninsula
PublicationThe study of scintillation-causing ionospheric irregularities is important to mitigate their effects on satellite communications. It is also important due to the spatial and temporal variability of these irregularities, given that their characteristics differ from one region to another. This study investigates the spatial and temporal characteristics of L1 amplitude scintillation-causing ionospheric irregularities over the Eastern...
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New Type of Small Broad-Band Internal Antenna for Third Generation Mobile Phone Handsets.
PublicationW pracy przedstawiono nową szerokopasmową antenę łatową przeznaczoną dla telefonów komórkowych trzeciej generacji. Proponowana struktura zawiera obwód (rezonator) w kształcie litery U i zaliczana jest do klasy PIFA (planar inverted-F antenna). W trakcie procesu projektowania przeprowadzono szereg symulacji elektromagnetycznych (metoda momentów), których wyniki zweryfikowano w oparciu o pomiary charakterystyk wykonanego prototypu....
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Band structure, Born effective charges, and lattice dynamics of CuInS2 from ab initio calculations
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Forecasting values of cutting power for the sawing process of impregnated pine wood on band sawing machine
PublicationW artykule przedstawiono prognozowane wartości mocy skrawania dla pilarki taśmowej (ST100R firmy STENNER), które są stosowane w polskich tartakach. Wartości mocy skrawania oszacowano dla drewna sosny zwyczajnej (Pinus sylvestris L.), które zostało poddane impregnacji. Dla porównania wyznaczono również wartości mocy skrawania dla drewna niezaimpregnowanego. Wartości te określono za pomocą innowacyjnej metody prognozowania sił skrawania,...
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Microfluidic SIW-Based Tunable Self-Diplexing Antenna for Sub-6 GHz Band Applications
PublicationThis work introduces a novel frequency tunable self-diplexing antenna (SDA) design based on substrate integrated waveguide (SIW) technology. A modified A-shaped slot is employed on the cavity’s top plane, which is excited by two independent 50 Ω microstrip feed lines to operate at each resonant frequency. The frequency flexibility of the proposed antenna allows for fine-tuning at each resonance frequency. The frequency flexibility...
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Analysis of specific cutting resistance while cutting frozen pine blocks with narrow-kerf stellite tipped saws on frame sawing machines.
PublicationPrzedstawiono wyniki analizy oporów skrawania drewna zmrożonego podczas przecierania pryzm sosnowych na pilarce ramowej za pomocą cienkich pił. Badania prowadzono dla temperatur drewna -5 st. C, -20 st. C oraz dla porównania w temperaturze +18 st. C. Wilgotność drewna wynosiła 30%. Zaobserwowano znaczacy wzrost oporów skrawania wraz ze spadkiem jego temperatury.
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Empty in summer, crowded during migration? Structure of assemblage, distribution pattern and habitat use by bats (Chiroptera: Vespertilionidae) in a narrow, marine peninsula
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Toward Wide-Band High-Resolution Analog-to-Digital Converters Using Hybrid Filter Bank Architecture
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RSS-Based DoA Estimation in 802.11p Frequency Band Using ESPAR Antenna and PPCC-MCP Method
PublicationIn this paper, the concept of direction of arrival (DoA) estimation using electronically steerable parasitic array radiator (ESPAR) antenna designed to operate in IEEE 802.11p vehicular communication standard has been investigated with respect to different possible elevation angles of a radio frequency (RF) signal impinging the antenna. To this end, two different possible sets of the 3D antenna radiation patterns have been used...
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Person Tracking in Ultra-Wide Band Hybrid Localization System Using Reduced Number of Reference Nodes
PublicationIn this article a novel method of positional data integration in an indoor hybrid localization system combining inertial navigation with radio distance measurements is presented. A point of interest is the situation when the positional data and the radio distance measurements are obtained from less than thee reference nodes and it is impossible to unambiguously localize the moving person due to undetermined set of positional equations....
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Hydrophobic PVDF hollow fiber membranes with narrow pore size distribution and ultra-thin skin for the fresh water production through membrane distillation
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Embedded device for indoor positioning of mobile terminals in ISM 2.4 GHz frequency band integrated with ESPAR antenna
PublicationIn the era of multifunctional mobile phones, wireless positioning is one of the most important branches of telecommunications development. This functionality is possible thanks to global positioning systems such as GPS, whose services are available to every average user. Global systems, however, suffer from their low accuracy in confined environments such as forests and building interiors. A popular...
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Bandwidth-Controllable Third-Order Band Pass Filter Using Substrate Integrated Full- and Semi-Circular Cavities
PublicationThe article presents a novel circular substrate integrated waveguide (SIW) bandpass filter (BPF) with controllable bandwidth. The proposed BPF is configured using two microstrip feedlines, semi- circular SIW cavities, capacitive slots, and inductive vias. The circular cavity is bisected into two halves, with the two copies thereof being cascaded. Two bisected and cascaded structures obtained this way are subsequently connected...
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Structural modification and band gap engineering of carbon nano-onions via sulphur doping: Theoretical DFT study
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Revisional bariatric surgery after adjustable gastric band: a multicenter Polish Revision Obesity Surgery Study (PROSS)
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Application of In-Syringe Dispersive Liquid–Liquid Microextraction and Narrow-Bore Tube Dispersive Liquid–Liquid Microextraction for the Determination of Trace Amounts of BTEX in Water Samples
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Cu-Doped Layered Double Hydroxide Constructs the Performance-Enhanced Supercapacitor Via Band Gap Reduction and Defect Triggering
PublicationLayered double hydroxides (LDHs) are regarded as the excellent electrode materials for supercapacitors because of their high theoretical capacitance and abundance. However, the poor conductivity and limited reaction kinetics of LDHs restrict their practical application severely. Herein, Cu is chosen from groups VIII/IB/IIB as dopants for Co-based LDH (CuCo-LDH). The designed metal–organic framework-derived hierarchical CuCo-LDH...
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Adrian Bekasiewicz dr hab. inż.
PeopleAdrian Bekasiewicz received the MSc, PhD, and DSc degrees in electronic engineering from Gdansk University of Technology, Poland, in 2011, 2016, and 2020, respectively. In 2014, he joined Engineering Optimization & Modeling Center where he held a Research Associate and a Postdoctoral Fellow positions, respectively. Currently, he is an Associate Professor with Gdansk University of Technology, Poland. His research interests include...
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Bonding of Molybdenum(V) to Poly(ethylene-co-methacrylic acid) Ionomers from X- and W-Band ESR and IR Spectroscopies
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A 1-nS 1-V Sub-1-µW Linear CMOS OTA with Rail-to-Rail Input for Hz-Band Sensory Interfaces
PublicationThe paper presents an operational transconductance amplifier (OTA) with low transconductance (0.62–6.28 nS) and low power consumption (28–270 nW) for the low-frequency analog front-ends in biomedical sensor interfaces. The proposed OTA implements an innovative, highly linear voltage-to-current converter based on the channel-length-modulation effect, which can be rail-to-rail driven. At 1-V supply and 1-Vpp asymmetrical input driving,...