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dr hab. inż. Łukasz Kulas
Employment
- Pełnomocnik Rektora ds. pozysk. i realizacji proj. at Faculty of Electronics, Telecommunications and Informatics
- Associate professor at Department of Microwave and Antenna Engineering
Publications
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total: 109
Catalog Publications
Year 2018
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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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RSS-based DoA Estimation Using ESPAR Antennas and Interpolated Radiation Patterns
PublicationIn this letter, it is shown how an algorithm, which employs received signal strength (RSS) values in order to estimate direction-of-arrival (DoA) of impinging signals in wireless sensor network (WSN) nodes equipped with electronically steerable parasitic array radiator (ESPAR) antennas, can easily be improved by applying an interpolation algorithm to radiation patterns recorded in the calibration phase of the DoA estimation process....
Year 2017
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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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Improved jamming resistance using electronically steerable parasitic antenna radiator
PublicationThis paper presents an idea of using an Electronically Steerable Parasitic Antenna Radiator (ESPAR) for jamming suppression in IEEE 802.11b networks. Jamming (intentional interference) attacks are known to be effective and easy to perform, which may impose connectivity problems in applications concerning Internet of Things (IoT). In our paper, theoretical considerations are presented and the results of experiments performed in...
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Simple 2-D Direction-of-Arrival Estimation Using an ESPAR Antenna
PublicationIn this letter, it has been shown how an electronically steerable parasitic array radiator (ESPAR) antenna can be used for 2-D direction-of-arrival (DoA) estimation employing received signal strength (RSS) values only. The proposed approach relies on changes in RSS values recorded at the antenna output port observed for different vertical and horizontal directions, while antenna’s main beam sweeps 360° area around the ESPAR antenna. Based...
Year 2016
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Measurement of distance, velocity and angle of arrival using FMCW-CW combined waveform
PublicationA procedure of tacking small flying object based on a general principle of FMCW and Doppler radar is presented. In order to increase measurement range, this technique uses active signal source on the moving object. For simultaneous measurements of distance, radial velocity and direction (AoA) as well as simplified synchronization a combined FMCW-CW waveform is proposed. The presented measurement system was realized and verified...
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Single-Anchor Indoor Localization Using ESPAR Antenna
PublicationIn this paper a new single-anchor indoor localization concept employing Electronically Steerable Parasitic Array Radiator (ESPAR) antenna has been proposed. The new concept uses a simple fingerprinting algorithm adopted to work with directional main beam and narrow minimum radiation patterns of ESPAR antenna that scans 360° area around the base station, while the signal strength received from a mobile terminal is being recorded...
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UHF ESPAR antenna for simple Angle of Arrival estimation in UHF RFID applications
PublicationAn electronically switched beam antenna for localization of passive UHF RFID tags based on a simple Angle of Arrival (AoA) technique is proposed‥ Detailed antenna design and realization are presented together with corresponding simulations and measurement results. Experimental tests with passive UHF RFID tag show the validity of theoretical assumptions for application of the antenna in UHF RFID based localization systems.
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Wireless multimodal localization sensor for industrial applications
PublicationThis paper presents the concept and design of a wireless multimodal localization sensor for hybrid localization systems combining vision-based, radio-based and inertial techniques in order to alleviate problems in harsh and complex industrial environments. It supports two radio technologies, 868 MHz UHF RFID and 2.4 GHz WSN, for positioning purposes and communications. The sensor includes LED light transmitters for vision-based...
Year 2015
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Efficient algorithm for blinking LED detection dedicated to embedded systems equipped with high performance cameras
PublicationThis paper presents the concept and implementation of an efficient algorithm for detection of blinking LED or similar signal sources. Algorithm is designed for embedded devices equipped with high performance cameras being a part of an indoor positioning embedded system. An algorithm to be implemented in such a system should be efficient in terms of computational power what is hard to be achieved when large amount of data from camera...
Year 2014
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Enhanced switched parasitic antenna with switched active monopoles for indoor positioning systems
PublicationThis paper presents the concept of enhanced reduced-size steerable antenna array with two rows of switched active and passive elements. Designed array is similar to ESPAR antenna but it has a set of switched monopoles instead of central one. It is intended for 2.4 GHz ISM applications with emphasis on indoor positioning systems (IPS). Proposed antenna provides improved radiation parameters and reduced dimensions in comparison to...
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RF Indoor Positioning System Supported by Wireless Computer Vision Sensors
PublicationIn this paper the possibility of increase the accuracy of RF fingerprinting indoor tracking system by the use of additional information from simple vision system is examined. As the distances in signal space differs from ones in real environment the ambiguity in decision process of fingerprinting algorithm can occur when set of closest distances between tag and map points in signal space corresponds to big distances differences...
Year 2013
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Design, Realization and Measurements of Enhanced Performance 2.4 GHz ESPAR Antenna for Localization in Wireless Sensor Networks
PublicationThis paper presents the design, realization and measurements of an Electronically Steerable Parasitic Array Radiator (ESPAR) antenna with enhanced performance of estimating the incoming signal direction. Designed antenna is dedicated for 2.4 GHz ISM applications with emphasis on Wireless Sensor Networks (WSN). Proposed antenna provides different radiation patterns by proper configuration of the parasitic elements. Thus, several...
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Influence of a Radio Frequency on RF Fingerprinting Accuracy Based on Ray Tracing Simulation
PublicationIn this paper the influence of a radio signal frequency on performance of Indoor Positioning System based on fingerprinting has been examined using ray-tracing simulations. It has been simulated how spatial distribution of an RF signal strength change with the signal’s frequency. The results were used to show its’ impact on the behavior of localization algorithms that are employing RSS measurements to determine node’s position...
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Verification of ESPAR Antennas Performance in the Simple and Calibration Free Localization System
PublicationThis paper presents the results of simulations and measurements of an indoor localization system that uses Electronically Steerable Parasitic Array Radiator (ESPAR) antennas with switched directional beam. Proposed antennas are dedicated for 2.4GHz ISM low-cost applications where determination of the incoming signal is required. The antennas performance is analyzed and verified with relation to positioning methods based on the...
Year 2012
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A Review of Antennas for Indoor Positioning Systems
PublicationThis paper provides a review of antennas applied for indoor positioning or localization systems. The desired requirements of thoseantennas when integrated in anchor nodes (reference nodes) are discussed, according to different localization techniques and theirperformance. The described antennas will be subdivided into the following sections according to the nature of measurements:received signal strength (RSS), time of flight (ToF),...
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Enhancing Performance of Switched Parasitic Antenna for Localization in Wireless Sensor Networks
PublicationThis paper presents an Electronically Steerable Parasitic Array Radiator (ESPAR) antenna with enhanced performance of estimating the incoming signal direction. Designed antenna is dedicated for 2.4 GHz ISM applications with emphasis on Wireless Sensor Networks (WSN). The limitations of the existing design approach are illustrated, as well as perspectives and challenges of the proposed solution in relation to the localization in...
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Influence of realistic antenna radiation pattern on rf fingerprinting accuracy
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Low Power Baseband Processor for M2M Reconfigurable Radio Test Platform
PublicationSoftware Defined Radio (SDR) is becoming more andmore frequently used technique for wireless communication. Itfacilitates as fast prototyping and is a versatile method fordeveloping new communication systems. SDR can be realizedbased on high computational capacity platform, where powerconsumption is no a primary concern like i.e. DVB or BTStransmitters. Another trend are low power systems, whereavailable power in reduced and more...
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Macro-elements and Model Order Reduction for Efficient Three-Dimensional FEM Analysis
PublicationAn efficient model order reduction (MOR) methodology for three dimensional vector finite element method (FEM) is developed to accelerate simulations of the structures containing features that cause strong variations of mesh density. As the result of presented algorithm, FEM subsystems of equations corresponding to the selected refined region are converted into a very compact sets of linear equations, called macro-elements.Numerical...
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Reduced order models in computational electromagnetics (in memory of Ruediger Vahldieck)
PublicationThis paper reviews research of Ruediger Vahldieck's group and the group at the Gdansk University of Technology in the area of model order reduction techniques for accelerating full-wave simulations. The applications of reduced order models to filter design as well as of local and nested(multilevel) macromodels for solving 3D wave equations and wave-guiding problems using finite difference and finite element methods are discussed.
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Reliable testbed for indoor positioning systems
PublicationThis paper proposes a test environment for indoor localization system, based on radio wave propagation prosperities. The following sections presents variety of problems from the assessment of the existing localization system to the analysis of inconveniences which occur when comparison of different localization systems is implemented. The problem is associated with different testing environments presented in published papers is...
Year 2011
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A New Type of Macro-Elements for Efficient Two-Dimensional FEM Analysis
PublicationThis letter deals with a model order reduction technique applicable for driven and eigenvalue problems solved using the finite element method (FEM). It allows one to efficiently compute electromagnetic parameters of structures comprising small features that require strong local mesh refinement. The subdomains of very fine mesh are separated from the global domain as so called macro-elements that undergo model reduction. The macro-elements...
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A Novel Modal Technique for Time and Frequency Domain Analysis of Waveguide Components
PublicationW pracy zaprezentowano, nową i szybką metodę analizy komponentów falowodowych. Metoda opiera się na kombinacji metody różnic skończonych, metody dekompozycji dziedziny obliczeniowej, redukcji rzędu modelu oraz dyskretnych rozwinięć funkcyjnych. Przedstawiona technika pozwala na skrócenie czasu analizy układu nawet o dwa rzędy wielkości w stosunku do poprzednich algorytmów.
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Analysis of microstructured optical fibers using compact macromodels
PublicationW niniejszym artykule zaproponowano nową technikę analizy światłowodów fotonicznych. Zaprezentowany algorytm jest kombinacją metody redukcji rzędu modelu oraz techniki dyskretnych rozwinięć funkcyjnych i pozwala w znaczącym stopniu zmniejszyć liczbę zmiennych (nawet do 85%), redukując (nawet 16 krotnie) czas symulacji.
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Macromodeling in Finite Differences
PublicationRozdział opisuje technikę wykorzystania procesu makromodelowania (wykorzystanie makromodelu do opisu równań różnicowych) w analizie różnic skończonych w dziedzinie czasu. Zawarte informacje pozwalają na samodzielne zaimplementowanie metody i pokazują możliwości poprawienia uzyskiwanych wyników.
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Testbed for development and verification of hybrid localization systems
PublicationIn this paper a testbed for development and verification of hybrid localization systems is presented. It allows for systematic analysis of hybrid localization methods and speed up the development of new schemes. The proposed testbed platform is composed of subsystem for sequential data collection and testing infrastructure that can be used for investigating the localization mechanisms in controllable environment.
Year 2010
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A universal IT system architecture for servicing, collecting, storing, processing and presenting data from wireless devices
PublicationIn the article we present a universal IT system architecture, which allows one to develop, based on mobile and multiplatform JAVA language, applications capable of working with many different wireless systems in an easy and effective way. Modular system architecture supports efficient data processing and enables convenient presentation of chosen parameters. Additionally, proposed IT system architecture provides easy adoption to...
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Advanced Macromodel Matrix Structure Cloning for FDTD
PublicationWe propose an improved macromodel-based techniquefor efficient analysis of the structures based on PhotonicCrystals (PhC). The technique involves a new structure of thecoupling matrix and advanced cloning of not only the macromodel matrices, but also the coupling matrices SE and SH.The method allows one to shorten considerably the preprocessingtime, the RAM usage and also the iterating speed of performingFDTD. With this...
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Hybrid RFID system
PublicationOpis koncepcji zintegrowanego systemu RFID w połączeniu z innymi technologiami sensorów tworzących hybrydowy system RFID.
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Improving the accuracy of subgridding scheme in finite differences method based on Legendre polynomials expansion
PublicationIn this article the Legendre polynomials have been used to interpolate the field at the boundary of the meshes of different densities. The numerical verification of the proposed technique has been carried out in frequency domain. It has been shown that the accuracy of the presented method is very high and stable - the error monotonically decreases as a function of the refinement factor.
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Localization in wireless sensor networks using switched parasitic antennas
PublicationA switched parasitic monopole antenna for 2.4 GHz ISM applications is design and investigated in this paper. One of the most promising applications for such switched-beam antennas is localization in wireless sensor networks (WSN). It is demonstrated that the use of this antenna improves accuracy of localization algorithms and allows for reduction of the number of reference nodes in localization system.
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Low cost microwave X-band generator
PublicationA low cost microwave X-band generator for educational purposes was designed and built. Its simple construction and user's interface makes it suitable for a student laboratory.The generator is based on a single frequency conversion concept. It uses a digitally tunable PLL chip for intermediate frequency generation and an active frequency multiplier for frequency conversion. The generator covers 9,7 - 11 GHz part of the X frequency...
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Macromodels for efficient FEM simulations of waveguides and resonators
PublicationThis paper introduces a novel technique for enhancing the efficiency of the finite element method (FEM) by incorporating special modules, called macromodels, into the standard eigenvalue formulation. The number of unknowns in the separated macromodel subdomain can be significantly reduced by orthogonal projection, using the efficient nodal order reduction algorithm. The idea of macromodels implementation is demonstrated on a simple...
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New RFID readers for scalable RFID system
PublicationRFID systems gives the opportunity to have wide access control integrated with the monitoring of people and goods flow. System's scalability is one of the most important features in such systems as they enable large scale deployments. The concept of the proposed reader's architecture employs new RFID transceivers and microcontrollers, security algorithms which gives very high functionality at low price. Special treatment of system's...
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Pattern matching localization in ZigBee wireless sensor networks.
PublicationLokalizacja typu Pattern matching w sieciach sensorów bezprzewodowych ZigBee.Prezentacja metod implementacji algorytmów lokalizacji. Praktyczne zastosowanie i testowanie lokalizacji sieci ZigBee.
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Reduced-order models in the finite element analysis
PublicationA novel technique of incorporating macromodels into finite element electromagnetic analysis of waveguide components is presented. Macromodels are generated by using a model order reduction algorithm (ENOR), which results in significant decrease of the number of variables, that describe the computational region. Proposed technique allows for using a few independent macromodels as well as to duplicating one macromodel in many subregions...
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Wireless paging system
PublicationAssistance to patients at hospitals and nursing homesoften encounters problems related to obtaining information onthe current needs of the patient. Traditionally, patient informshospital stuff by wire and wireless paging systems. WirelessPaging Systems allow one to overcome the limitations of theirwire counterparts, which include high installation costs (cabling)and lack of patient mobility. The main difference betweenpresented...
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WSN for intelligent street lighting system
PublicationIn this article authors propose to apply WSN to intelligent street lighting system. As a result of such a combination one obtains a system designed to increase functionality of light installations for a wide range of applications and introduce a platform for new additional services, which meets current and future user needs. The system is composed of WSN nodes integrated with light sources based on high power LED diodes, which...
Year 2008
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A technique of stabilizing FDTD-subgridding algorithm using reciprocity principle
PublicationW artykule przedstawiono wykorzystanie zasady wzajemności w procesie stabilizacji zagęszczania siatki dla fdtd. Metoda ta oryginalnie służyła tylko do sprawdzenia stabilności algorytmów zagęszczających siatki fdtd, jednak pozwala ona na zmianę współczynnika sprzężenia pomiędzy polami występującymi na brzegach w ten sposób, że algorytm siatkowania jest stabilny. Zaprezentowana metoda została zweryfikowana testami numerycznymi pod...
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Grouping macromodels by using multilevel model order reduction
Publicationartykuł pprezentuje nowatorską technikę grupowania makromodeli dla metody fdtd. nowa technika bazuje na schemacie wielopoziomowej redukcji rzędu modeli. grupowanie makromodeli pozwala na zwiększenie szybkości symulacji w porównaniu do niezgrupowanych makromodeli, zapewniając przy tym porównywalną dokładność.
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Implementation of matrix-type FDTD algorithm on a graphics accelerator
PublicationArtykuł prezetuje implementację algorytmu FDTD w postaci macierzowej przeznaczonej dla kart graficznych. Wykazany został wzrost efektywności obliczeń numerycznych w odniesieniu do implementacji przeznaczonej dla procesora komputerowego.
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Localization in wireless sensor networks based on zigbee platform
PublicationW artykule porównano dwie różne metody lokalizacji w sieciach sensorów bezprzewodowych. Jedną z metod jest implementacja sprzętowa algorytmu w układzie nadawczo odbiorczym CC2431. Drugą metodą jest implementacja programowa. Wyniki testów przeprowadzonych na otwartym terenie oraz w pomieszczeniach zamkniętych zostały przedstawione i porównane w pracy.
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Methods of improving accuracy of indoor localization systems based on 802.11 standard infrastructure
PublicationArtykuł dotyczy różnorodnych metod zwiększania dokładności istniejących już algorytmów lokalizacji, implementowanych w standardzie WLAN 802.11. W pracy przedstawiono nowatorskie rozwiązanie wykorzystujące elementy poprawiające dokładność, takie jak: algorytmy, adaptacja środowiska, filtrowanie sygnałów.
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Modular wireless sensor network platform for RF transceiver evaluation
PublicationArtykuł przedstawia modułową technikę projektowania sieci sensorów bezprzewodowych. Uniwersalne połączenia występujące pomiędzy modułami pozwalają na zaprojektowanie nowej wersji sieci w przeciągu kilku dni zamiast tygodni. Na bazie wymienionej metodologii skonstruowane została platforma pozwalająca testować różnego rodzaju układy nadawczo odbiorcze pracujące na częstotliwościach RF.
Year 2006
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Analysis of a high-quality photonic crystal resonator
PublicationArtykuł przedstawia kompleksową analizę rezonatora 2D o wysokiej dobroci uzyskanego dzięki zastosowaniu fotonicznych kryształów. Struktura rezonatora została zoptymalizowana w celu osiągnięcia maksymalnej dobroci. Analiza została wykonana przy pomocy metody FDTD z zaimplementowanymi makromodelami, a wyniki poddano następnie obróbce cyfrowej w oparciu o technikę GPOF. Taka kombinacja zastosowanych metod okazała się bardzo efektywna...
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Model order reduction for subgridding in fdtd scheme
PublicationW artykule zaprezentowana została technika pozwalająca na uzyskanie wysokiej rozdzielczości w metodzie FDTD. Prezentowany algorytm jest połączeniem metod redukcji rzędu modelu i lokalnych zagęszczeń zaimplementowanych do FDTD. Pozwala to zmniejszyć liczbę użytych zmiennych stanu, a także skrócić krok czasowy, co skutkuje znacznie krótszym czasem symulacji, niż w przypadku klasycznej metody FDTD.
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Simple and accurate field interpolation in finite difference methods
PublicationW artykule wprowadzono nową metodę interpolacji pól w metodzie różnic skończonych. Metoda jest prosta i daje wyniki bardziej dokładne niż w przypadku interpolacji liniowej. Proponowana metoda interpolacji może zostać użyta do poprawienia dokładności takich metod, jak subgridding.
Year 2005
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Low-Reflection Subgridding
PublicationArtykuł przedstawia technikę umieszczania makromodeli w trójwymiarowej siatce dyskretyzacji metody różnic skończonych. Umożliwia ona łączenie obszarów siatki o różnym kroku dyskretyzacji. Zastosowana prosta interpolacja liniowa wraz z kolokacją pól sąsiadujących ze sobą podobszarów prowadzi do uzyskania małego współczynnika odbicia od obszaru z gęstą siatką.
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Makromodele w metodzie różnic skończonych.
PublicationPrzedstawiono nową technikę zwiększającą dokładność i szybkość pełnofalowej analizy złożonych struktur mikrofalowych wykorzystującą technikę redukcji rzędu modelu ang. Model Order Reduction (MOR) w połączeniu z metodami różnic skończonych (FDTD, FDFD). Zastosowanie wysokorozdzielczego algorytmu FDTD i FDFD zawierającego makromodele pozwala na dobre odwzorowanie zmienności pól elektromagnetycznych w całej dziedzinie obliczeniowej....
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