Search results for: TRIPLE-BAND ANTENNAS
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Accelerated simulation-driven design optimisation of compact couplers by means of two-level space mapping
PublicationIn this study, the authors discuss a robust and efficient technique for rapid design of compact couplers. The approach exploits two-level space mapping (SM) correction of an equivalent circuit model of the coupler structure under design. The first SM layer (local correction) is utilised to ensure good matching between the equivalent circuit and the electromagnetic model at the component level. Subsequent global correction allows...
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Low-cost data-driven modelling of microwave components using domain confinement and PCA-based dimensionality reduction
PublicationFast data-driven surrogate models can be employed as replacements of computationally demanding full-wave electromagnetic simulations to facilitate the microwave design procedures. Unfortunately, practical application of surrogate modelling is often hindered by the curse of dimensionality and/or considerable nonlinearity of the component characteristics. This paper proposes a simple yet reliable approach to cost-efficient modelling...
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An Analysis of Elliptical-Rectangular Multipatch Structure on Dielectric-Coated Confocal and Nonconfocal Elliptic Cylinders
PublicationA rigorous analysis of the resonance frequency problem of an elliptical-rectangular microstrip structure mounted on dielectric-coated elliptic conducting cylinder, with electrically small radius, is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. The analysis is carried out considering the expansion of the field as a series of Mathieu functions. The complex resonance frequencies of...
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Hybrid technique for the analysis of circular waveguide junctions loaded with ferrite posts
PublicationThis study presents a hybrid technique for the analysis of circular waveguide junctions loaded with axially symmetrical ferrite posts of irregular shape. The method is based on a combination of the finite-difference frequency- domain technique with a mode-matching technique. The proposed approach is validated by comparing the presented results with numerical ones obtained from commercial software. The application of a cylindrical...
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Rapid design of miniaturised branch-line couplers through concurrent cell optimisation and surrogate-assisted fine-tuning
PublicationIn this study, the authors introduce a methodology for low-cost simulation-driven design optimisation of highly miniaturised branch-line couplers (BLCs). The first stage of their design approach exploits fast concurrent optimisation of geometrically dependent, but electromagnetically isolated cells that constitute a BLC. The cross-coupling effects between the cells are taken into account in the second stage, where a surrogate-assisted...
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Rapid multi-objective antenna design using point-by-point Pareto set identification and local surrogate models
PublicationAntenna design is inherently a multicriterial problem.Determination of the best possible tradeoffs between conflicting objectives (a so-called Pareto front), such as reflection response, gain, and antenna size, is indispensable from the designer’s point of view, yet challenging when high-fidelity electromagnetic (EM) simulations are utilized for performance evaluation. Here, a novel and computationally...
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Electromagnetic Problems Requiring High-Precision Computations
PublicationAn overview of the applications of multiple-precision arithmetic in CEM was presented in this paper for the first time. Although double-precision floating-point arithmetic is sufficient for most scientific computations, there is an expanding body of electromagnetic problems requiring multiple-precision arithmetic. Software libraries facilitating these computations were described, and investigations requiring multiple-precision...
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Rapid multi-objective design optimisation of compact microwave couplers by means of physics-based surrogates
PublicationThe authors introduce a methodology for fast multi-objective design optimisation of miniaturised microwave couplers. The approach exploits the surrogate-based optimisation paradigm with an underlying low-fidelity model constructed from an equivalent circuit of the structure under consideration, corrected through implicit and frequency space mapping. A fast prediction tool obtained this way is subsequently optimised by a multi-objective...
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Efficient Complex Root Tracing Algorithm for Propagation and Radiation Problems
PublicationAn efficient complex root tracing algorithm for propagation and radiation problems is presented. The proposed approach is based on a discretization of Cauchy’s Argument Principle and its generalization to the C × R space. Moreover, an engagement of the tracing process with a global root finding algorithm recently presented in the literature is performed. In order to confirm a validity and efficiency of the proposed technique, a...
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Analytical Expression for the Time-Domain Green's Function of a Discrete Plane Wave Propagating in the 3-D FDTD Grid
PublicationIn this paper, a closed-form expression for the time-domain dyadic Green’s function of a discrete plane wave (DPW) propagating in a 3-D finite-difference time-domain (FDTD) grid is derived. In order to verify our findings, the time-domain implementation of the DPW-injection technique is developed with the use of the derived expression for 3-D total-field/scattered-field (TFSF) FDTD simulations. This implementation requires computations...
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Accurate modelling of microwave structures using shape-preserving response prediction
PublicationArtykuł prezentuje metodologię dokładnego modelowania struktur mikrofalowych. Jest to zmodyfikowana wersja techniki opartej na procedurze przewidywania odpowiedzi z zachowaniem kształtu (shape-preserving response prediction, SPRP), która oszacowuje odpowiedź struktury mikrofalowej otrzymanej poprzez kosztowną obliczeniowo symulację elektromagnetyczną za pomocą taniego obliczeniowo modelu tejże struktury. Modyfikacja polega na wykorzystaniu...
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A new approach to a fast and accurate design of microwave circuits with complex topologies
PublicationA robust simulation-driven design methodology of microwave circuits with complex topologies has been presented. The general method elaborated is suitable for a wide class of N-port unconventional microwave circuits constructed as a deviation from classic design solutions. The key idea of the approach proposed lies in an iterative redesign of a conventional circuit by a sequential modification and optimisation of its atomic building...
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Accuracy of the Discrete Green's Function Formulation of the FDTD Method
PublicationThis paper reports an evaluation of the accuracy of the discrete Greens function (DGF) formulation of the finite-difference time-domain (FDTD) method. Recently, the closed-form expression for the DGF and its efficient numerical implementation were presented, which facilitates applications of the DGF in FDTD simulations of radiation and scattering problems. So far, the accuracy of the DGF formulation of the FDTD method has been...
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Local response surface approximations and variable-fidelity electromagnetic simulations for computationally efficient microwave design optimisation
PublicationIn this study, the authors propose a robust and computationally efficient algorithm for simulation-driven design optimisation of microwave structures. Our technique exploits variable-fidelity electromagnetic models of the structure under consideration. The low-fidelity model is optimised using its local response surface approximation surrogates. The high-fidelity model is refined by space mapping with polynomial interpolation of...
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Design of novel microstrip directional coupler for differential signal decoupling
PublicationThis study describes a concept of a novel microstrip directional coupler for differential signal decoupling, which can be used to digital signal overhearing on printed-circuit-boards. The complete design method is proposed with rules given analytically. Considered methodology is suitable for synthesis of couplers with low coupling factors, which have negligible influence on the transmission in main line. Theoretical considerations...
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Resonance Frequency Calculation of a Multilayer and Multipatch Spherical Microstrip Structure Using a Hybrid Technique
PublicationThis communication offers a rigorous analysis of the resonance frequency problem of a spherical microstrip structure mounted on a multilayer, dielectric-coated metallic sphere, with an electrically small radius. The structure consists of single or multiple metallic patches with arbitrary shapes. A full-wave analysis is employed with the use of proposed hybrid approach, combining the finite-difference technique with a spectral domain...
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Scattering From a Cylindrical Object of Arbitrary Cross Section With the Use of Field Matching Method
PublicationA simple and intuitive solution to scattering problems in shielded and open structures is presented. The main idea of the analysis is based on the direct field matching technique involving the usage of projection of the fields at the boundary on a fixed set of orthogonal basis functions. Different convex shapes and various obstacle materials are considered to verify the validity of the method in open and closed structures. The...
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AEGIS – Mobile Device for Generating Electromagnetic Curtain for Special Applications and Countering the Threats of RCIED
PublicationIn the article the assumptions, design and realization of the technological demonstrator of a mobile device for generating an electromagnetic curtain (with a cryptonym AEGIS) were presented, both in the area of hardware and software. The device is designed to block the radio communication systems by which it is possible to detonate the Radio Controlled Improvised Explosive Devices (RCIEDs). The preliminary laboratory tests of the...
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Automatyczna georeferencja w oparciu o rozpoznawanie i dopasowywanie niejednorodnych zbiorów punktów
PublicationW pracy przedstawiono kształt prototypowego systemu przeznaczonego do przeprowadzania automatycznej georeferencji obrazów pozyskiwanych na drodze obserwacji lotniczej lub satelitarnej. System przewiduje przeprowadzanie georeferencji w trybie nienadzorowanym w oparciu o rozpoznawanie i dopasowywanie kształtów o charakterze zbiorów punktów. Omówiono komponenty oraz zaproponowano algorytmy możliwe do zastosowania w poszczególnych...
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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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60 GHz Microstrip Van Atta Arrays for Millimeter Wave Identification and Localization
PublicationIn this paper performance comparison of co-polarized and cross-polarized microstrip Van Atta arrays working in the 60 GHz frequency range is presented. They can be treated as simple chipless RFID tags with frequency response based identification. Tags with three different nominal resonance frequencies of 57, 62 and 67 GHz are designed by scaling optimized base model. Designed 62 GHz co-polarized and cross-polarized arrays with...
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LOS and NLOS identification in real indoor environment using deep learning approach
PublicationVisibility conditions between antennas, i.e. Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) can be crucial in the context of indoor localization, for which detecting the NLOS condition and further correcting constant position estimation errors or allocating resources can reduce the negative influence of multipath propagation on wireless communication and positioning. In this paper a deep learning (DL) model to classify LOS/NLOS...
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Measurements of Path Loss in Off-Body Channels in Indoor Environments
PublicationThis paper presents a measurements of the path loss for validation of a statistical model for off-body radio channels in an indoor multipath environment, which considers the distance dependent mean path loss, and describes body shadowing and fast fading components in a statistical way. The measurement equipment and propagation indoor environment have been presented. Two different bodies and five static and two walking scenarios...
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UAV spectrometer reflectance and leaf area index for vegetation near Gdynia, Poland
Open Research DataReflectance data from the UAV flights with UV-VIS spectrometer along with leaf area index measurements for vegetaion near Gdynia, Poland.
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The luminescence study of Bi-doped Cs2AgInCl6 double perovskite.
Open Research DataHere, we report a halide precursor acid precipitation method to synthesize Cs2AgIn1−xBixCl6 (x = 0, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, and 1) microcrystals. Cs2AgInCl6 and Bi derivative double perovskites show broadband white light emission via self-trapped excitons (STEs) and have achieved the highest internal quantum efficiency of up to 52.4% at...
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Structure and Stability Characterization of Natural Lake Pigments Made from Plant Extracts and Their Potential Application in Polymer Composites for Packaging Materials
PublicationNatural dyes were extracted from various plant sources and converted into lake pigments based on aluminum and tin. Three different plants (weld, Persian berries, and Brazilwood) were chosen as representative sources of natural dyes. High-performance liquid chromatography (HPLC) and triple-quadrupole mass spectrometry (QqQ MS) were used to identify dyestuffs in the raw extracts. The natural dyes and lake pigments were further characterized...
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Photoelectrochemical properties of BIMEVOX (ME=Cu, Zn, Mn) electrodes in contact with aqueous electrolyte
PublicationLayered oxide Bi4O2O11 and mixed oxides of bismuth, vanadium and a third metal (ME = Cu, Zn, Mn) were synthesized and characterized using XRD, Raman and SEM. The energy band gap (Eg) of samples determined using UV–VIS reflectance spectra equals to 2.46, 2.34, 2.27 and 2.18 eV for Bi4V2O11, BICUVOX (Bi2V1 − xCuxO5.5 − 3x/2), BIZNVOX (Bi2V1 − xZnxO5.5 − 3x/2) and BIMNVOX (Bi2V1 − xMnxO5.5 − x/2) (x = 0.1), respectively. Open circuit...
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Ferro- and antiferro-magnetism in (Np, Pu)BC
PublicationTwo new transuranium metal boron carbides, NpBC and PuBC, have been synthesized. Rietveld refinements of powder XRD patterns of {Np,Pu} BC confirmed in both cases isotypism with the structure type of UBC. Temperature dependent magnetic susceptibility data reveal antiferromagnetic ordering for PuBC below T-N = 44 K, whereas ferromagnetic ordering was found for NpBC below T-C = 61 K. Heat capacity measurements prove the bulk character...
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Mutual Clutter Suppression Techniques for FM Sonars
PublicationThe article presents methods that help in the elimination of mutual clutter as well as the consequences of two FM sounding signal sonars operating in the same body of water and frequency band. An in-depth analysis of mutual clutter was carried out. The effects of sounding signal differentiation were determined, as was the Doppler effect on mutual clutter suppression. One of the methods analysed is of particular interest in a situation...
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Structural properties of hypothetical CeBa2Cu3O7 compound from LSDA+DMFT calculations
PublicationThe hypothetical stoichiometric CeBa2Cu3O7 (Ce123) compound, which has not been synthesized as a single phase yet, was studied by the density functional theory (DFT). We utilized a method which merges the local spin density approximation (LSDA) with the dynamical mean-field theory (DMFT) to account for the electronic correlations. The LSDA+DMFT calculations were performed in the high-temperature range. The particular emphasis was...
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Molecular level interpretation of excess infrared spectroscopy
PublicationInfrared (IR) spectroscopy is an invaluable tool in studying intermolecular interactions in solvent mixtures. The deviation of the IR spectrum of a mixture from the spectra of its pure components is a sensitive measure of the non-ideality of solutions and the modulation of intermolecular interactions introduced by mutual influence of the components. Excess IR spectroscopy, based on the established notion of excess thermodynamic...
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Exploring the interfacial effects at the ETL/perovskite boundary in the semitransparent perovskite solar cells
PublicationThe recent focus has been made on the perovskite solar cells (PSCs) with an inverted configuration, where substantial improvements have been already achieved. However, the p–i–n structure needs a buffer layer for most of the configurations to modify the work-function of a deposited electrode. Additionally and very importantly, such a layer can also serve as a protective film that improves a stability of solar cells. Here, we study...
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Influence of the boron doping level on the electrochemical oxidation of the azo dyes at Si/BDD thin film electrodes
PublicationIn this study the efficiency of electrochemical oxidation of aromatic pollutants, such as reactive dyes, at boron-doped diamond on silicon (Si/BDD) electrodes was investigated. The level of [B]/[C] ratio which is effective for the degradation and mineralization of selected aromatic pollutants, and the impact of [B]/[C] ratio on the crystalline structure, layer conductivity and relative sp3/sp2 coefficient of a BDD electrode were...
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Synthesis, crystal structure and cytotoxic activity of ruthenium(II) piano-stool complex with N,N-chelating ligand
PublicationA mononuclear compound of the general formula [(η6-p-cymene)RuIICl(2,2′-PyBIm)]PF6 has been synthesized from a bidentate N,N-donor ligand, viz. 2,-(2′-pyridyl)benzimidazole (2,2′-PyBIm) and the corresponding chloro-complex [(η6-p-cymene)Ru(μ-Cl)Cl]2 (precursor). The isolated coordination compound was characterized by IR, UV–vis and 1H, 13C NMR spectroscopies. The single crystal X-ray analysis of the complex reveals that the asymmetric...
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GaN Nanowire Array for Charge Transfer in Hybrid GaN/P3HT:PC71BM Photovoltaic Heterostructure Fabricated on Silicon
PublicationAbstract: We demonstrate that a GaN nanowire array can be used for efficient charge transfer between the organic photovoltaic layer and silicon in a Si/GaN/P3HT:PC71BM inverted hybrid heterostructure. The band alignment of such a material combination is favorable to facilitate exciton dissociation, carrier separation and electron transport into Si. The ordered nature of the GaN array helps to mitigate the intrinsic performance...
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Importance of Specific Heat Characterization when Reporting New Superconductors: An Example of Superconductivity in LiGa2Rh
PublicationWe show that the full-Heusler compound LiGa2Rh is a superconductor with Tc = 2.4 K. The new superconductor was found as a result of an intuition-based extension of a database search for superconductors that looked for the presence of peaks in the electronic band structure near the Fermi energy. The measurement of the entropy loss during the transition from the nonsuperconducting to the superconducting state, a straightforward measurement...
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Microstrip four-port circulator using a ferrite coupled line section
PublicationThis paper describes an alternative configuration of a four-port circulator realized in a microstrip ferrite coupled line technology. The proposed fully planar device employs two three-port circulators consisting of a ferrite coupled line junction and T junction. Both circulators are connected through the same arm, hence, the problem of anti-parallel magnetization met in this type of circulators is avoided without the increase...
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Threshold photoelectron studies of isoxazole over the energy range 9.9-30 eV
PublicationThe threshold photoelectron spectrum of the isoxazole molecule, C3H3NO has been measured over the photon energy range 9.9-30 eV with the use of synchrotron radiation. In the 9.9-10.8 eV range, corresponding to photoionization from the highest occupied molecular orbital 3a"(π3), seven well resolved vibrational series have been observed and their modes are tentatively assigned. A strong adiabatic ionization, with an energy of 11.132...
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Adaptive estimation of the transformer stray capacitances for DC–DC converter modelling
PublicationNew low cost and accurate estimation method of transformer stray capacitances for wide band DC–DC converter modelling and design is proposed. The Wiener filter (WF) method is applied to estimate the transformer impedance – referred to the selected transformer winding configurations. Laboratory tests are used to adapt the filter, that is to find optimal impedance which minimises mean square error between measured, noise perturbed...
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Determination of the tram track axis using a multi receiver GNSS measurement system
PublicationThis article refers to research, that has been conducted by an interdisciplinary research team from the Gdańsk University of Technology and the Maritime University in Gdynia since 2009. These investigation concerns the determination of a railway track axis using the mobile satellite measurement technique. Following the dynamic development of GNSS techniques, that could be seen in the last decade, the team carried out further experiments...
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Electromagnetic Simulation with 3D FEM for Design Automation in 5G Era
PublicationElectromagnetic simulation and electronic design automation (EDA) play an important role in the design of 5G antennas and radio chips. The simulation challenges include electromagnetic effects and long simulation time and this paper focuses on simulation software based on finite-element method (FEM). The state-of-the-art EDA software using novel computational techniques based on FEM can not only accelerate numerical analysis, but...
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Low-Cost Open-Hardware System for Measurements of Antenna Far-Field Characteristics in Non-Anechoic Environments
PublicationExperimental validation belongs to the most important steps in the development of antenna structures. Measurements are normally performed in expensive, dedicated facilities such as anechoic chambers, or open-test sites. A high cost of their construction might not be justified when the main goal of antenna verification boils down to demonstration of the measurement procedure, or rough validation of the simulation models used for...
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An Efficient Framework For Fast Computer Aided Design of Microwave Circuits Based on the Higher-Order 3D Finite-Element Method
PublicationIn this paper, an efficient computational framework for the full-wave design by optimization of complex microwave passive devices, such as antennas, filters, and multiplexers, is described. The framework consists of a computational engine, a 3D object modeler, and a graphical user interface. The computational engine, which is based on a finite element method with curvilinear higher-order tetrahedral elements, is coupled with built-in...
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Analysis of the Impact of Galileo Observations on the Tropospheric Delays Estimation
PublicationIn this study we present analysis of the impact of Galileo observations on the ZTD and tropospheric gradients estimation. The tropospheric parameters were obtained in various scenarios, which differ from each other only in used satellite systems: Galileo-only, GPS-only, GPS/Galileo, GPS/GLONASS and GPS/GLONASS/Galileo. Then, comparative analysis between Galileo-only solution and the other ones, was carried out. As a reference,...
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Direction-of-Arrival Estimation Using an ESPAR Antenna with Simplified Beam Steering
PublicationIn this paper, it has been shown, how electronically steerable parasitic array radiator (ESPAR) antenna, in which beam steering is done in a simple way, can be used for directionof- arrival (DoA) estimation of an unknown signal impinging the antenna. The concept is based on an ESPAR antenna having twelve parasitic elements, in which beam switching is realized by RF switches providing required loads to its parasitic elements. Numerical...
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Surface Science - 2023/2024
e-Learning CoursesThe course is not a full time lecture but on the consultation/handouts. The consulations are held every two weeks. The course is based on the Springer textbook: Surface Science An Introduction Downloadable at: https://link.springer.com/book/10.1007/978-3-662-05179-5 (PG network or vpn access) The goal of the subject is the presentation of basic problems resulting from he existence of interfacebetween material objects...
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STUDY OF CuO AND V2O5 EFFECT ON IR SPECTRA OF POLYCRYSTALLINE BISMUTH NIOBATE
PublicationBismuth niobate (BiNbO4) ceramics were fabricated by mixed oxide method and sintered by presureless sintering method. BiNbO4 ceramics doped with V2O5 additive in amount 0.125 wt%, 0.250 wt% and 1 wt% of was sintered at T = 910°C whereas BiNbO4 ceramics doped with 2 wt% of CuO additive was sintered at T = 890°C and T = 910°C. It was found that V2O5 additive improved morphology of the ceramic samples. However, the chemical composition...
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Simple and low-cost wireless voting system
PublicationThis paper presents the concept of a simple and low-cost wireless voting system working in the 868 MHz frequency band. The described system is dedicated to general shareholders assemblies but it can be easily adapted for other applications. The main advantage is its simplicity and mobility as it consists solely of three components - voting modules, a base station and a PC application from which the whole system is mamaged. This...
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Simple and low-cost wireless voting system
PublicationThis paper presents the concept of a simple and low-cost wireless voting system working on the 868 MHz frequency band. Described system is dedicated to general shareholders assemblies but it can be easily adapted for other applications. The main advantage is its simplicity and mobility as it consists solely of three components - voting modules, base station and a PC application from which the whole system is managed. This architecture...
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The geometry of free-standing titania nanotubes as a critical factor controlling their optical and photoelectrochemical performance
PublicationTitanium dioxide nanotubes are regarded as one of the most important functional materials and due to their unique electronic properties, chemical stability and photocorrosion resistance, they find applications in, for example, highly efficient photocatalysis or perovskite solar cells. Nevertheless, modification of TiO2 nanotubes is required to overcome their main drawback, i.e. large energy bandgap (>3.2 eV) limiting their ability...