Wyszukiwarka
Filtry
wszystkich: 1014
wybranych: 899
-
Katalog
- Publikacje 899 wyników po odfiltrowaniu
- Czasopisma 12 wyników po odfiltrowaniu
- Osoby 39 wyników po odfiltrowaniu
- Wynalazki 1 wyników po odfiltrowaniu
- Projekty 6 wyników po odfiltrowaniu
- Laboratoria 1 wyników po odfiltrowaniu
- Zespoły Badawcze 2 wyników po odfiltrowaniu
- Kursy Online 37 wyników po odfiltrowaniu
- Dane Badawcze 17 wyników po odfiltrowaniu
Filtry wybranego katalogu
Wyniki wyszukiwania dla: INEXPENSIVE ANTENNA
-
Inexpensive Helical Antenna for Global Navigation Satellite Systems
PublikacjaZaprezentowane 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...
-
PCR-ELISA: inexpensive alternative to quantitative PCR
PublikacjaPCR-ELISA (polymerase chain reaction-enzyme linked immunosorbent assay), a combination of PCR and ELISA methods, has been used since late 1980s. The technique is based on specially labelled DNA fragments which are captured by specific DNA sequences and detected by antibodies. The whole procedure of PCR-ELISA is divided into three steps: DNA extraction, PCR reaction and detection by ELISA. The method has been found as very specific...
-
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...
-
Multi-objective optimization of expensive electromagnetic simulation models
PublikacjaVast majority of practical engineering design problems require simultaneous handling of several criteria. For the sake of simplicity and through a priori preference articulation one can turn many design tasks into single-objective problems that can be handled using conventional numerical optimization routines. However, in some situations, acquiring comprehensive knowledge about the system at hand, in particular, about possible...
-
Miniature reconfigurable antenna
PublikacjaThis work concerns the design of a miniature, low-profile reconfigurable antenna based on Huygens metamaterial sources for frequency f0 = 2.45 GHz. Two planar Huygens sources were designed consisting of near-field resonators. Sources are excited from a specially designed reconfigurable control system. Thanks to the two PIN diodes, the system can realize two cardioid radiation characteristics with...
-
Extraction of antenna pattern from near field antenna measurements distorted by undesired emission
PublikacjaIn this paper authors present experimental correction of antenna pattern obtained from near field measurements when they are distorted by determined electromagnetic emission. Such situation may be met e.g. when feeding or supply subsystem interacts with antenna radiation pattern due to self-emission. Presented results of experiments show effectiveness of extraction of antenna pattern utilizing near field antenna measurements.
-
Broadband Sonar with a Cylindrical Antenna
PublikacjaSkutkiem wzrostu szerokości widma sygnałów w sonarach z płaskimi antenami jest wzrost szerokości odchylanych wiązek, jeżeli beamformer dokonuje kompensacji faz tylko na częstotliwości środkowej widma. W artykule przedstawiono wyniki obliczeń, które odpowiadają na pytanie, czy podobny efekt występuje w szerokopasmowych sonarach z anteną cylindryczną. Obliczenia przeprowadzono dla anten nadawczych o szerokich wiązkach i anten odbiorczych...
-
A Concept for Safe and Less Expensive Acceleration of a Marine Steam Turbine Start-up
PublikacjaThis paper analyses the issue of accelerated start-up of a marine steam turbine, which is an important problem because the start-up of a steam machine involves the combustion of fuel that is not transformed into useful energy. To find novel technologies that offer improvements in this aspect is essential due to restrictions on reducing ship emissions. Thus, the shorter the start-up time, the better for the environment and economy....
-
Elliptical slot UWB monopole antenna
PublikacjaThe UWB monopole antenna with elliptical radiating slot end and microstrip feeding line terminated with radial stub have been designed, fabricated and measured. The antenna show return loss less than -12 dB in the whole UWB bandwidth. Linearity of the reflection coefficient phase product have also been achieved. Radiation patterns of the antenna measured at three selected frequency points indicated regular, approximately omni directional...
-
Expedited Globalized Antenna Optimization by Principal Components and Variable-Fidelity EM Simulations: Application to Microstrip Antenna Design
PublikacjaParameter optimization, also referred to as design closure, is imperative in the development of modern antennas. Theoretical considerations along with rough dimension adjustment through supervised parameter sweeping can only yield initial designs that need to be further tuned to boost the antenna performance. The major challenges include handling of multi-dimensional parameter spaces while accounting for several objectives and...
-
Multi-Beam Antenna for Ka-Band CubeSat Connectivity Using 3-D Printed Lens and Antenna Array
PublikacjaIn this paper, the design of a passive multi-beam lens antenna is proposed for the CubeSat space communication system as an alternative application of a 2-D microstrip antenna array that has originally been designed for a 39 GHz 5 G MU-MIMO system. The half-ellipsoid lens is 3-D printed using stereolithography (SLA) technology. The antenna prototype is capable of selecting the main beam between 16 different directions with a gain...
-
Strategies can be expensive too! The value spread and asset allocation in global equity markets
Publikacja -
Efficient knowledge-based optimization of expensive computational models using adaptive response correction
PublikacjaComputer simulation has become an indispensable tool in engineering design as they allow an accurate evaluation of the system performance. This is critical in order to carry out the design process in a reliable manner without costly prototyping and physical measurements. However, high-fidelity computer simulations are computationally expensive. This turns to be a fundamental bottleneck when it comes to design automation using numerical...
-
A Multi-Fidelity Surrogate-Model-Assisted Evolutionary Algorithm for Computationally Expensive Optimization Problems
PublikacjaIntegrating data-driven surrogate models and simulation models of different accuracies (or fideli-ties) in a single algorithm to address computationally expensive global optimization problems has recently attracted considerable attention. However, handling discrepancies between simulation models with multiple fidelities in global optimization is a major challenge. To address it, the two major contributions of this paper include:...
-
Design-Oriented Constrained Modeling of Antenna Structures
PublikacjaFast surrogate models are crucially important to reduce the cost of design process of antenna structures. Due to curse of dimensionality, standard (data-driven) modeling methods exhibit serious limitations concerning the number of independent geometry parameters that can be handled but also (and even more importantly) their parameter ranges. In this work, a design-oriented modeling framework is proposed in which the surrogate is...
-
UWB planar antenna dipole in the sandwich configuration
PublikacjaW pracy przedstawiono wyniki badań nad planarną anteną dipolową o ramionach kołowych, przeznaczoną dla systemu UWB. Ramiona dipola umieszczono pomiędzy dwoma warstwami dielektryka (konfiguracja kanapki) uzyskując redukcję wymiarów anteny. Stwierdzono, że impedancja wejściowa jest mniejsza, niż w przypadku pojedynczego podłoża, co umożliwia łatwiejsze dopasowanie anteny do toru zasilającego. Współczynnik odbicia w całym paśmie...
-
Ridged horn antenna for ground penetrating radar
PublikacjaOmówiono modyfikację tuby grzbietowej polegającą na jej wypełnieniu dielektrykiem, w celu wykorzystania do układu pozwalającego na poszukiwanie obiektów znajdujących się pod ziemią. Omówiono badania, które doprowadziły do opracowania konstrukcji anteny z wypełnieniem dielektrycznym. Przedstawiono wyniki testu takiej anteny w układzie do detekcji obiektu metalowego umieszczonego pod ziemią.
-
Sierpinski Monopole Antenna - Uniplanar Feeding Technique.
PublikacjaPrzedstawiono różne techniki zasilania monopolowych anten fraktalnych typu Sierpinskiego. Zaproponowano nowe sposoby zasilania: poprzez linię współosiową ze zmodyfikowaną rozszerzoną płaszczyzną masy oraz poprzez linię współosiową i falowód koplanarny. W obu przypadkach możliwa była znaczna miniaturyzacja struktury. Wykonane i przebadane prototypy anten potwierdziły przydatność przedstawionych rozwiązań.
-
Simulation-Driven Design of Microstrip Antenna Subarrays
PublikacjaA methodology for computationally efficient simulation-driven design of microstrip antenna subarrays is presented. Our approach takes into account the effect of the feed (e.g., a corporate network) on the subarray side lobe level and allows adjusting both radiation and reflection responses of the structure under design within a single automated process. This process is realized as surrogate-based optimization that produces designs...
-
Modelling of mutual coupling in microstrip antenna arrays fed by microstrip line. Modelowanie sprzężenia w szykach anten mikropaskowych zasilanych przez linie mikropaskowe.
PublikacjaPrzedstawiono wyniki modelowania sprzężenia pomiędzy prostokątnymi radiatorami mikropaskowymi w szyku liniowym anten zasilanych przez linie mikropaskowe. Zaproponowano schemat zastępczy sprzężenia w postaci kombinacji linii transmisyjnych wraz z sękami zwartymi i rozwartymi. Pokazano, że schemat taki dobrze modeluje sprzężenie w wąskim pasmie częstotliwości ok. 4%. Wyniki modelowania sprawdzono eksperymentalnie poprzez pomiary...
-
Direction-of-Arrival Estimation Using an ESPAR Antenna with Simplified Beam Steering
PublikacjaIn 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...
-
Design optimization of novel compact circular polarization antenna
PublikacjaThe 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...
-
A structure and design of a novel compact UWB MIMO antenna
PublikacjaIn 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...
-
Novel structure and design of compact UWB slot antenna
PublikacjaIn 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...
-
A Geometrically Simple Compact Wideband Circularly Polarized Antenna
PublikacjaA 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...
-
Broadband Microstrip Patch Antenna with Reduced Transversal Size
PublikacjaW 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...
-
Design of UWB coplanar antenna with reduced ground plane
PublikacjaW 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...
-
Double-ridged horn antenna with sinusoidal ridge profile
PublikacjaPrzedstawiono 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...
-
Compact CPW-fed Sierpinski fractal monopole antenna.
PublikacjaZaproponowano 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.
-
Diagnostics of thermal processes in antenna systems of broadcast stations
PublikacjaDiagnostics 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...
-
Small Antenna Design Using Surrogate-Based Optimization
PublikacjaIn 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...
-
Compact antenna array comprising fractal-shaped microstripradiators
PublikacjaA 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...
-
Single-Anchor Indoor Localization Using ESPAR Antenna
PublikacjaIn 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...
-
Knowledge-based performance-driven modeling of antenna structures
PublikacjaThe 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...
-
Reconfigurable Antennas for Trustable Things
PublikacjaIn modern applications, the Internet of Things plays a significant role in increasing the productivity, effectiveness or safety and security of people and assets. Additionally, the reliability of Internet of Things components is crucial from the application point of view, where a resilient and low-latency network is needed. This can be achieved by utilizing reconfigurable antennas to enhance the capabilities of the wireless sensor...
-
Atomistic Surrogate-Based Optimization for Simulation-Driven Design of Computationally Expensive Microwave Circuits with Compact Footprints
PublikacjaA robust simulation-driven design methodology for computationally expensive microwave circuits with compact footprints has been presented. The general method introduced in this chapter is suitable for a wide class of N-port un-conventional microwave circuits constructed as a deviation from classic design solutions. Conventional electromagnetic (EM) simulation-driven design routines are generally prohibitive when applied to numerically...
-
Low-Cost Quasi-Global Optimization of Expensive Electromagnetic Simulation Models by Inverse Surrogates and Response Features
PublikacjaConceptual design of contemporary high-frequency structures is typically followed by a careful tuning of their parameters, predominantly the geometry ones. The process aims at improving the relevant performance figures, and may be quite expensive. The reason is that conventional design methods, e.g., based on analytical or equivalent network models, often only yield rough initial designs. This is especially the case for miniaturized...
-
Dual-band antenna with improved gain for WLAN and ISM applications
PublikacjaIn this Letter, a dual-band antenna with an improved gain is proposed. The structure features 9.7 and 10.4 dBi gain within 2.4 GHz to 2.5 GHz and 5 GHz to 6 GHz bands, respectively. This makes it suitable for WLAN and ISM applications. The structure comprises an asymmetrical pair of radiators and slots suspended over a reflector. The antenna is optimised in a two-stage process using a trust-region-based gradient search algorithm....
-
Expedited optimization of antenna input characteristics with adaptive Broyden updates
PublikacjaSimulation-driven adjustment of geometry and/or material parameters is a necessary step in the design of contemporary antenna structures. Due to their topological complexity, other means, such as supervised parameter sweeping, does not usually lead to satisfactory results. On the other hand, rigorous numerical optimization is computationally expensive due to a high cost of underlying full-wave electromagnetic (EM) analyses, otherwise...
-
Expedited antenna optimization with numerical derivatives and gradient change tracking
PublikacjaDesign automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)-driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable...
-
Compact Dual-Polarized Corrugated Horn Antenna for Satellite Communications
PublikacjaIn this paper, a structure and design procedure of a novel compact dual-polarized corrugated horn antenna with high gain and a stable phase center for satellite communication is presented. The antenna incorporates an Ortho-Mode Transducer (OMT), a mode converter, and a corrugated structure. The compact OMT section is designed to be fed by standard WR-75 waveguides. The proposed compact design utilizes only ten corrugated slots...
-
Computationally Efficient Design Optimization of Compact Microwave and Antenna Structures
PublikacjaMiniaturization is one of the important concerns of contemporary wireless communication systems, especially regarding their passive microwave components, such as filters, couplers, power dividers, etc., as well as antennas. It is also very challenging, because adequate performance evaluation of such components requires full-wave electromagnetic (EM) simulation, which is computationally expensive. Although high-fidelity EM analysis...
-
Performance-Based Nested Surrogate Modeling of Antenna Input Characteristics
PublikacjaUtilization of electromagnetic (EM) simulation tools is mandatory in the design of contemporary antenna structures. At the same time, conducting designs procedures that require multiple evaluations of the antenna at hand, such as parametric optimization or yield-driven design, is hindered by a high cost of accurate EM analysis. To certain extent, this issue can be addressed by utilization of fast replacement models (also referred...
-
A Broadband Circularly Polarized Wide-Slot Antenna with a Miniaturized Footprint
PublikacjaThis letter presents a novel and simple feeding technique for exciting orthogonal components in a wide-slot antenna. In this technique, a rectangular bracket-shape parasitic strip is placed at the open end of the straight microstrip line to excite the fundamental horizontal and vertical components of the circular polarization (CP). The proposed technique—when employed in conjunction with the asymmetrical geometry of coplanar waveguide...
-
Simple Superstrate Antenna for Connectivity Improvement in Precision Farming Applications
PublikacjaIn 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...
-
Detection and Mitigation of GPS Spoofing Based on Antenna Array Processing
PublikacjaIn this article authors present an application of spatial processing methods for GPS spoofing detection and mitigation. In the first part of this article, a spoofing detection method, based on phase delay measurements, is proposed. Accuracy and precision of phase delay estimation is assessed for various qualities of received signal. Spoofing detection thresholds are determined. Efficiency of this method is evaluated in terms of...
-
Some Aspects in the Model of a Wire Antenna by Using the Mathcad Language
PublikacjaW artykule omówiono możliwość modelowania anteny prętowej przy wykorzystaniu programu Mathcad. Przedstawiono sposób rozwiązywania równania różniczkowo-całkowego na przykładzie równania Pocklingtona. Artykuł zawiera szczegółowy opis modelu, uzyskane wyniki obliczeniowe i wnioski na temat użyteczności metody i problemów związanych ze zbieżnością zastosowanych algorytmów numerycznych.
-
Antenna Optimization Using Machine Learning with Reduced-Dimensionality Surrogates
PublikacjaIn modern times, antenna design has become more demanding than ever. The escalating requirements for performance and functionality drive the development of intricately structured antennas, where parameters must be meticulously adjusted to achieve peak performance. Often, global adjustments to geometry are necessary for optimal results. However, direct manipulation of antenna responses evaluated with full-wave electromagnetic (EM)...
-
Specification-Oriented Automatic Design of Topologically Agnostic Antenna Structure
PublikacjaDesign of antennas for modern applications is a challenging task that combines cognition-driven development of topology intertwined with tuning of its parameters using rigorous numerical optimization. However, the process can be streamlined by neglecting the engineering insight in favor of automatic de-termination of structure geometry. In this work, a specification-oriented design of topologically agnostic antenna is considered....
-
Millimeter Wave Negative Refractive Index Metamaterial Antenna Array
PublikacjaIn this paper, a novel negative refractive index metamaterial (NIM) is developed and characterized. The proposed metamaterial exhibits negative effective permittivity (εeffe) and negative effective permeability (µeffe) at millimeter wave frequency of 28GHz. This attractive feature is utilized to enhance the gain of a microstrip patch antenna (MPA). Two thin layers of 5 5 subwavelength unit cell array of NIM are placed above a...