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Wyniki wyszukiwania dla: ANTENY
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Excitation of Circularly Polarized Wave via Single-Feed Metasurface-Integrated Compact Antenna for Internet of Things
PublikacjaA compact circularly polarized (CP) quasi-omnidirectional antenna is introduced for internet of things (IoT). The structure consists of two components implemented on FR-4 substrates, and sep-arated by an air gap: one printed with a rectangular patch fed through a matching network, and another with a metasurface and a ground plane. Two different methods for impedance matching are employed. An equivalent circuit model of the antenna...
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Ultra-Compact Self-Quadruplexing Microfluidically Frequency Reconfigurable Slot Antenna Using Half-Mode SIW
PublikacjaIn this brief, the design of an ultra-compact self-quadruplexing frequency reconfigurable antenna (SQFRA) utilizing a half-mode substrate-integrated waveguide (HMSIW) and microfluidic channels is discussed. Four HMSIW cavities fed by four microstrip lines and slots are used to construct a highly compact antenna. The microstrip feedings to the HMSIW cavities are applied in such a way that the proposed antenna exhibits self-quadruplexing...
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Compact Substrate-Integrated Hexagonal Cavity-Backed Self-Hexaplexing Antenna for Sub-6 GHz Applications
PublikacjaA self-multiplexing SIW antenna based on hexagonal SIW cavity is proposed. The self-hexaplexing antenna consists of different sizes of resonating elements, which provide the hexaband operations. The antenna resonates at 5 GHz, 5.17 GHz, 5.32 GHz, 5.53 GHz, 5.62 GHz, and 5.72 GHz by employing different slot lengths between the resonating elements. The proposed antenna provides the individual tunable characteristics of the operating...
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Filter-Hilbert Method for Automatic Correction of Non-Anechoic Antenna Measurements with Embedded Self-Calibration Mechanism
PublikacjaOne of the most important steps in the process of antenna development involves measurements of its prototype. Far-field performance of radiators is normally characterized in strictly controlled environments such as anechoic chambers which can ensure certification-grade accuracy. Unfortunately, they are also characterized by high construction costs which might not be justified for low-budget research and/or teaching-related activities....
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Metamaterial-Based Series-Fed Antenna with High Gain and Wideband Performance for Millimeter Wave Spectrum Applications
PublikacjaThis paper presents a high-gain, wideband series-fed antenna designed for 5G millimeter-wave (MMW) applications. The structure employs a substrate-integrated waveguide (SIW)-based power splitter and metamaterials (MMs). The power divider functions effectively at 27.5 GHz, exhibiting an impedance bandwidth from 26.9–28.6 GHz. The series-fed dipole is assembled on the SIW-based power splitter, incorporating four dipoles with varying...
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Efficient Simulation-Based Global Antenna Optimization Using Characteristic Point Method and Nature-Inspired Metaheuristics
PublikacjaAntenna structures are designed nowadays to fulfil rigorous demands, including multi-band operation, where the center frequencies need to be precisely allocated at the assumed targets while improving other features, such as impedance matching. Achieving this requires simultaneous optimization of antenna geometry parameters. When considering multimodal problems or if a reasonable initial design is not at hand, one needs to rely...
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Shielded HMSIW-based frequency-tunable self-quadruplexing antenna using different solid/liquid dielectrics
PublikacjaThis article proposes a frequency-tunable self-quadruplexing antenna based on a shielded half-mode substrate integrated waveguide (S-HMSIW). In order to reduce the size of the HMSIW cavity resonator and to obtain quad-band characteristics, a modied E-shaped slot is engraved on the top of the metal. The experimental validation is carried out after analyzing the data using a circuit model. Flexibility of each resonant frequency is...
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Frequency-Reconfigurable Hybrid SIW-Based Self-Diplexing Antenna Using Solid and Liquid Dielectric Loading
PublikacjaThis paper presents a novel frequencyreconfigurable self-diplexing antenna (SDA) utilizing a hybrid substrate-integrated waveguide (SIW). The antenna comprises a radiating slot, a feeding network, and a hybrid SIW cavity featuring half-mode circular and half-mode rectangular SIW structures. The unique feature of this antenna lies in its fine-tuning capability of each resonant frequency by inserting or injecting solid and liquid...
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Low-Cost Open-Hardware System for Measurements of Antenna Far-Field Characteristics in Non-Anechoic Environments
PublikacjaExperimental 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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Globalized Knowledge-Based Simulation-Driven Antenna Miniaturization Using Domain-Confined Surrogates and Dimensionality Reduction
PublikacjaDesign of contemporary antenna systems encounters multifold challenges, one of which is a limited size. Compact antennas are indispensable for the new fields of application such as inter-net of things or 5G/6G mobile communication. Still, miniaturization generally undermines elec-trical and field performance. When attempted through numerical optimization, it turns into a constrained problem with costly constraints requiring electromagnetic...
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Mutual Coupling Reduction in Antenna Arrays Using Artificial Intelligence Approach and Inverse Neural Network Surrogates
PublikacjaThis paper presents a novel approach to reduce undesirable coupling in antenna arrays using custom-designed resonators and inverse surrogate modeling. To illustrate the concept, two stand-ard patch antenna cells with 0.07λ edge-to-edge distance are designed and fabricated to operate at 2.45 GHz. A stepped-impedance resonator is applied between the antennas to suppress their mutual coupling. For the first time, the optimum values...
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Badanie i analiza układu antenowego dla potrzeb mobilnego urządzenia do wytwarzania kurtyny elektromagnetycznej
PublikacjaPrzedstawiono analizę układu antenowego, wchodzącego w skład prototypu mobilnego urządzenia do wytwarzania kurtyny elektromagnetycznej. Celem wykonania analizy było wyznaczenie położenia anten tworzących układ antenowy tak, aby uzyskać kompromis pomiędzy wzajemnym ich wpływem i rozmiarami masztu antenowego. Wzajemny wpływ anten oceniano z wykorzystaniem współczynnika S21 oraz charakterystyk promieniowania układu przez modelowanie...
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Primo non nocere - Die Neuevaluierung und Revitalisierung des alten Universitaetsgelaendes in Danzig
PublikacjaKonstruując kompleksowy program rozwoju kampusu zespół specjalistów PG musiał odpowiedzieć na wiele kluczowych pytań wpływających na ostateczne decyzje przestrzenne. Historyczna część kampusu - jej spójność przestrzenna jest prawnie chroniona i nie może być zakłócona. Dlatego przy konstruowaniu programu rewitalizacji dla tej strefy przyjęto za nadrzędną dewizę Primo Non Nocere. Aby zminimalizować ingerencję w zastaną strukturę...
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Postępy Akustyki // Advances in Acoustics rozdział: Doskonalenie metod detekcji i śledzenia ruchu obiektów podwodnych pasywnym sonarem dalekiego zasięgu z holowaną liniową anteną
PublikacjaDalekosiężne pasywne sonary z długimi holowanymi antenami są obecnie najlepszymi systemami do wykrywania obecności i określania namiarów na współczesne, ciche okręty podwodne. Dlatego są stosowane zarówno na dużych okrętach nawodnych jak i podwodnych mimo niewygód przy ich rozwijaniu, holowaniu i zwijaniu a także mimo zawiłości oraz niejednoznaczności wskazań (tylko namiary na cel - bez rozróżnienia lewej i prawej burty oraz brak...
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Vascular restenosis in coronary artery bypass grafting might be associated with VEGF-C/VEGFR-3 signaling pathway
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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
PublikacjaDetermination 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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Embedded device for indoor positioning of mobile terminals in ISM 2.4 GHz frequency band integrated with ESPAR antenna
PublikacjaIn 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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The role of depressive and anxiety symptoms in the evaluation of cardiac rehabilitation efficacy after coronary artery bypass grafting surgery
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Cytokeratin 8 in venous grafts: A factor of unfavorable long-term prognosis in coronary artery bypass grafting patients
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Regional resting state perfusion variability and delayed cerebrovascular uniform reactivity in subjects with chronic carotid artery stenosis
PublikacjaThe aim of this study was to assess regional perfusion at baseline and regional cerebrovascular resistance (CVR) to delayed acetazolamide challenge in subjects with chronic carotid artery stenosis.Sixteen patients (ten males) aged 70.94±7.71 with carotid artery stenosis ≥90% on the ipsilateral side and ≤50% on the contralateral side were enrolled into the study. In all patients, two computed tomography perfusion examinations were...
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A Wideband Corrugated Ridged Horn Antenna with Enhanced Gain and Stable Phase Center for X- and Ku-Band Applications
PublikacjaIn this letter, a structure and design procedure of a novel double-flared conical horn antenna with an improved gain and a stable phase center is presented. The antenna incorporates a hybrid ridged and corrugated structure. A double-ridged section is responsible for ensuring a wideband operation, whereas the corrugated section supports the hybrid mode. The antenna impedance bandwidth (VSWR < 2) is 6 GHz to 20 GHz. Excellent performance...
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Variable-Fidelity Simulation Models and Sparse Gradient Updates for Cost-Efficient Optimization of Compact Antenna Input Characteristics
PublikacjaDesign of antennas for the Internet of Things (IoT) applications requires taking into account several performance figures, both electrical (e.g., impedance matching) and field (gain, radiation pattern), but also physical constraints, primarily concerning size limitation. Fulfillment of stringent specifications necessitates the development of topologically complex structures described by a large number of geometry parameters that...
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Coronary artery disease, arterial stiffness, and myocardial work: what is the role of diabetes in this vicious circle? Authors’ reply
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Role of adenylate kinase 4 as a new metabolic regulator of pulmonary artery smooth muscle cells under hypoxia
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Improved-Efficacy EM-Driven Optimization of Antenna Structures Using Adaptive Design Specifications and Variable-Resolution Models
PublikacjaOptimization-driven parameter tuning is an essential step in the design of antenna systems. Although in many cases it is still conducted through parametric studies, rigorous numerical methods become a necessity if truly optimum designs are sought for, and the problem intricacies (number of variables, multiple goals, constraints) make the interactive approaches insufficient. The two practical considerations of electromagnetic (EM)-driven...
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An Innovative Antenna Array with High Inter Element Isolation for Sub-6 GHz 5G MIMO Communication Systems
PublikacjaA novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna’s footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted...
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Rapid Variable-Resolution Parameter Tuning of Antenna Structures Using Frequency-Based Regularization and Sparse Sensitivity Updates
PublikacjaGeometry parameter tuning is an inherent part of antenna design process. While most often performed in a local sense, it still entails considerable computational expenses when carried out at the level of full-wave electromagnetic (EM) simulation models. Moreover, the optimization outcome may be impaired if good initial design is not available. This paper proposes a novel approach to fast and improved-reliability gradient-based...
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Circular polarization diversity implementation for correlation reduction in wideband low-cost multiple-input-multiple-output antenna
PublikacjaIn this paper, a multiple-input-multiple-output (MIMO) antenna featuring circular polarization diversity, and designed on a common coplanar ground is presented. The proposed antenna design utilizes a coplanar waveguide (CPW) feeding technique with three parallel coplanar ground planes, and two feedlines in-between. For circular polarization (CP), quasi-loops are created by etching slots on the outermost ground planes. With this...
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Expedited Acquisition of Database Designs for Reduced-Cost Performance-Driven Modeling and Rapid Dimension Scaling of Antenna Structures
PublikacjaFast replacement models have been playing an increasing role in high-frequency electronics, including the design of antenna structures. Their role is to improve computational efficiency of the procedures that normally entail large numbers of expensive full-wave electromagnetic (EM) simulations, e.g., parametric optimization or uncertainty quantification. Recently introduced performance-driven modeling methods, such as the nested...
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Fast multi-objective design optimization of microwave and antenna structures using data-driven surrogates and domain segmentation
PublikacjaPurpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multi-objective setup are investigated. Design/methodology/approach Formulation of the multi-objective design problem oriented towards execution of the population-based metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics- and...
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Expedited Feature-Based Quasi-Global Optimization of Multi-Band Antenna Input Characteristics with Jacobian Variability Tracking
PublikacjaDesign of modern antennas relies—for reliability reasons—on full-wave electromagnetic simulation tools. In addition, increasingly stringent specifications pertaining to electrical and field performance, growing complexity of antenna topologies, along with the necessity for handling multiple objectives, make numerical optimization of antenna geometry parameters a highly recommended design procedure. Conventional algorithms, particularly...
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Analysis of circular polarization antenna design trade‐offs using low‐cost EM‐driven multiobjective optimization
PublikacjaCircular polarization (CP) antennas are vital components of modern communication systems. Their design involves handling several requirements such as low reflection and axial ratio (AR) within the frequency range of interest. Small size is an important criterion for antenna mobility which is normally achieved as a by‐product of performance‐oriented modifications of the structure topology. In this work, multiobjective optimization...
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Rapid multi-objective antenna design using point-by-point Pareto set identification and local surrogate models
PublikacjaAntenna 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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Scalability of surrogate-assisted multi-objective optimization of antenna structures exploiting variable-fidelity electromagnetic simulation models
PublikacjaMulti-objective optimization of antenna structures is a challenging task due to high-computational cost of evaluating the design objectives as well as large number of adjustable parameters. Design speedup can be achieved by means of surrogate-based optimization techniques. In particular, a combination of variable-fidelity electromagnetic (EM) simulations, design space reduction techniques, response surface approximation (RSA) models,...
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Recent advances in rapid multiobjective optimization of expensive simulation models in microwave and antenna engineering by Pareto front exploration
PublikacjaPractical engineering design problems are inherently multiobjective, that is, require simultaneous control of several (and often conflicting) criteria. In many situations, genuine multiobjective optimization is required to acquire comprehensive information about the system of interest. The most popular solution techniques are populationbased metaheuristics, however, they are not practical for handling expensive electromagnetic...
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Microfluidically Frequency-Reconfigurable Compact Self-Quadruplexing Tunable Antenna with High Isolation Based on Substrate Integrated Waveguide
PublikacjaThis communication presents a novel concept of microfluidically frequency-reconfigurable self-quadruplexing tunable antenna for quad-band applications. At the initial design stage, a substrate-integrated square cavity is divided into four unequal quarter-mode cavity resonators by inserting an X-shaped slot on the top surface of the cavity. Applying four 50-ohm microstrip feed-lines to these four quarter-mode cavity resonators enables...
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Fast Calibration-Free Single-Anchor Indoor Localization Based on Limited Number of ESPAR Antenna Radiation Patterns
Publikacja— In this article, we investigate how the calibrationfree single-anchor indoor localization algorithm developed for base stations equipped with electronically steerable parasitic array radiator (ESPAR) antennas can further be improved. By reducing the total number of ESPAR antenna radiation patterns used in localization process, one can significantly reduce the time needed for an object localization. Performed localization measurements...
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Model Management for Low-Computational-Budget Simulation-Based Optimization of Antenna Structures Using Nature-Inspired Algorithms
PublikacjaThe primary objective of this study is investigation of the possibilities of accelerating nature-inspired optimization of antenna structures using multi-fidelity EM simulation models. The primary methodology developed to achieve acceleration is a model management scheme which the level of EM simulation fidelity using two criteria: the convergence status of the optimization algorithm, and relative quality of the individual designs...
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Ultra-Wideband Vivaldi Antenna with an Integrated Noise-Rejecting Parasitic Notch Filter for Online Partial Discharge Detection
PublikacjaPower transformers and gas-insulated switchgear (GIS) play crucial roles in electrical power grids. However, they may suffer from degradation of insulation material due to wear and tear, leading to their imminent failure. Partial discharges (PDs) are an initial sign of insulation materials degradation which emit signals spanning various physical domains, including electromagnetic. PDs are temporally narrow, high-frequency, stochastic...
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A Dual-Polarized 39 GHz 4x4 Microstrip Antenna Array for 5G MU-MIMO Airflight Cabin Connectivity
PublikacjaThis paper presents the design, fabrication, and experimental validation of a 39 GHz dual-polarized 4x4 microstrip antenna array. The array consists of 16 slot coupled circular microstrip patches, fed through SMPS connectors. The procedure requiring a reduced number of cables for measurement of the uniformly excited antenna array is also presented. The array exhibits 18 dBi peak gain and 2.9 GHz reflection bandwidth and is intended...
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The Way One Defines Specification Matters: On the Performance Criteria for Efficient Antenna Optimization in Aggregated Bi-Objective Setups
PublikacjaDesign of antenna structures for real-world applications is a challenging task that often involves addressing multiple design requirements at a time. Popular solution approaches to this class of problems include utilization of composite objectives. Although configuration of such functions has a significant effect on the cost and performance of the optimization, their specific structure is normally determined based on engineering...
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Initial Report on Numerical Modeling of Blood Flow in Myocardial Bridge Region of Coronary Artery: Concept of Model Validation
PublikacjaThe paper presents a numerical method of blood flow simulation within the coronary artery covered by the myocardial bridge. The myocardial bridge is a congenital coronary abnormality caused by the blood vessel location under one of the heart muscles. In this case, the blood flow within the vessel is partially disturbed which can cause several consequences. The presented numerical simulation allowed us to estimate the blood flow...
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Detection of broadband signals in the field of aperture and array systems.
PublikacjaAnteny i szyki anten w dolnopasmowych systemach hydroakustycznych wnoszą istotne zniekształcenia liniowe wpływające na możliwości detekcji sygnałów szerokopasmowych. W artykule analizowany jest charakter takich zniekształceń metodą przestrzenno - czasowych odpowiedzi impulsowych. Sygnał odbierany w różnych kierunkach przestrzeni poddano filtracji na dwa sposoby z filtrem dopasowanym do sygnału nadawanego i filtrem dopasowanym...
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ANALIZA UWARUNKOWAŃ PROPAGACYJNYCH W RADIOWYCH SIECIACH BAN Z PRZESTRZENNYM ODBIOREM ZBIORCZYM
PublikacjaW referacie przedstawiono analizę uwarunkowań propagacyjnych w radiowych sieciach BAN typu off-body z odbiorem zbiorczym przestrzennym. Średnia wartość tłumienia znajduje się w przedziale [54.42 dB; 64.28 dB], różnica wartości tłumienia dla anten nasobnych wynosi [0.69 dB; 8.76 dB], odchylenie standardowe tłumienia średniego zawarta jest w przedziale [6.46 dB; 7.39 dB], natomiast współczynnik korelacji pomiędzy zanikami szybkozmiennymi...
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KUSATU: Kleine Untersuchungen zur Sprache des Alten Testaments und seiner Umwelt
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Angiotensin converting enzyme gene polymorphism is associated with severity of coronary artery disease in men with high total cholesterol levels
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Comparison of the effects of rosuvastatin monotherapy and atorvastatin-ezetimibe combined therapy on the structure of erythrocyte membranes in patients with coronary artery disease
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Patch size setup and performance/cost trade-offs in multi-objective antenna optimization using domain patching technique
PublikacjaA numerical study concerning multi-objective optimization of antenna structures using sequential domain patching (SDP) technique has been presented. We investigate the effect of various setups of the patch size on the operation of the SDP algorithm and possible trade-offs concerning the quality of the Pareto set found by SDP and the computational cost of the optimization process. Our considerations are illustrated using a UWB monopole...
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Accelerated Gradient-Based Optimization of Antenna Structures Using Multi-Fidelity Simulations and Convergence-Based Model Management Scheme
PublikacjaThe importance of numerical optimization has been steadily growing in the design of contemporary antenna structures. The primary reason is the increasing complexity of antenna topologies, [ a typically large number of adjustable parameters that have to be simultaneously tuned. Design closure is no longer possible using traditional methods, including theoretical models or supervised parameter sweeping. To ensure reliability, optimization...
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Low-Cost Yield-Driven Design of Antenna Structures Using Response-Variability Essential Directions and Parameter Space Reduction
PublikacjaQuantifying the effects of fabrication tolerances and uncertainties of other types is fundamental to improve antenna design immunity to limited accuracy of manufacturing procedures and technological spread of material parameters. This is of paramount importance especially for antenna design in the industrial context. Degradation of electrical and field properties due to geometry parameter deviations often manifests itself as, e.g.,...