Search results for: MICROWAVE TECHNOLOGY
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Magnetic field mapping along a NV-rich nanodiamond-doped fiber
PublicationIntegration of NV−-rich diamond with optical fibers enables guiding quantum information on the spin state of the NV− color center. Diamond-functionalized optical fiber sensors have been demonstrated with impressive sub-nanotesla magnetic field sensitivities over localized magnetic field sources, but their potential for distributed sensing remains unexplored. The volumetric incorporation of diamonds into the optical fiber core allows...
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Surface modification of PMMA polymer and its composites with PC61BM fullerene derivative using an atmospheric pressure microwave argon plasma sheet
PublicationThis paper presents the results of experimental investigations of the plasma surface modification of a poly(methyl methacrylate) (PMMA) polymer and PMMA composites with a [6,6]-phenyl-C61-butyric acid methyl ester fullerene derivative (PC61BM). An atmospheric pressure microwave (2.45 GHz) argon plasma sheet was used. The experimental parameters were: an argon (Ar) flow rate (up to 20 NL/min), microwave power (up to 530 W), number...
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Design-Oriented Two-Stage Surrogate Modeling of Miniaturized Microstrip Circuits with Dimensionality Reduction
PublicationContemporary microwave design heavily relies on full-wave electromagnetic (EM) simulation tools. This is especially the case for miniaturized devices where EM cross-coupling effects cannot be adequately accounted for using equivalent network models. Unfortunately, EM analysis incurs considerable computational expenses, which becomes a bottleneck whenever multiple evaluations are required. Common simulation-based design tasks include...
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Design of novel highly sensitive sensors for crack detection in metal surfaces: theoretical foundation and experimental validation
PublicationThe application of different types of microwave resonators for sensing cracks in metallic structures has been subject of many studies. While most studies have been focused on improving the sensitivity of planar crack sensors, the theoretical foundation of the topic has not been treated in much detail. The major objective of this study is to perform an exhaustive study of the principles and theoretical foundations for crack sensing...
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Computationally-Efficient Statistical Design and Yield Optimization of Resonator-Based Notch Filters Using Feature-Based Surrogates
PublicationModern microwave devices are designed to fulfill stringent requirements pertaining to electrical performance, which requires, among others, a meticulous tuning of their geometry parameters. When moving up in frequency, physical dimensions of passive microwave circuits become smaller, making the system performance increasingly susceptible to manufacturing tolerances. In particular, inherent inaccuracy of fabrication processes affect...
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Extending the Frequency Limit of Microstrip-Coupled CSRR Using Asymmetry
PublicationAbstract— This article explains the frequency limitation in designing microstrip circuits based on a complementary split-ring resonator (CSRR) and reports a novel technique for increasing its operating frequency, which makes the CSRR suitable for high-frequency applications. This study helps in synthesizing the dimensions of symmetric CSRR (SCSRR) and asymmetric CSRR (ACSRR) circuits, which shows the applicability of the proposed...
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Spurious Modes in Model Order Reduction in Variational Problems in Electromagnetics
PublicationIn this work, we address an everlasting issue in 2 model order reduction (MOR) in electromagnetics that has 3 remained unnoticed until now. Contrary to what has been 4 previously done, we identify for the very first time spurious 5 modes in MOR for time-harmonic Maxwell’s equations and 6 propose a methodology to remove their negative influence on the 7 reduced order model (ROM) response. These spurious modes 8 have nonzero resonance...
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Nitrogen-doped diamond thin films: potential application in Fabry-Pérot interferometer
PublicationIn this paper we present results of preliminary research of using nitrogen-doped diamond (NDD) films as reflective layer in Fabry-Pérot interferometer. NDD films were deposited on Si substrates by Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) with the use of CH4, H2 and N2 gas mixtures. During deposition process methane flow rate varied while nitrogen flow was constant. We performed series of measurements which showed...
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Optoelectronic system for investigation of cvd diamond/DLC layers growth
PublicationDevelopment of the optoelectronic system for non-invasive monitoring of diamond/DLC (Diamond-Like-Carbon) thin films growth during μPA ECR CVD (Microwave Plasma Assisted Electron Cyclotron Resonance Chemical Vapour Deposition) process is described. The system uses multi-point Optical Emission Spectroscopy (OES) and long-working-distance Raman spectroscopy. Dissociation of H2 molecules, excitation and ionization of hydrogen atoms...
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Fast multi-criterial statistical analysis and design optimization of compact microwave couplers
Publication—A rapid statistical analysis and yield estimation of compact microwave couplers involving multiple performance parameters has been presented. The analysis is realized using a fast surrogate model representing appropriate characteristic points of the coupler response. Because of less nonlinear dependence of the characteristic points on the structure geometry (compared to the original response, i.e., S-parameters vs. frequency),...
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A Compact and Lightweight Microwave Tilt Sensor Based on an SRR-Loaded Microstrip Line
PublicationIn this paper, the symmetry property of split ring resonators (SRRs) is exploited to develop a tilt sensor. The sensor is composed of an SRR-loaded microstrip line operating at microwave frequencies. It is shown that the depth of notch in the reflection characteristic of the microstrip is a function of the tilt angle of the SRR. Thus, it can be used for sensing inclination. The sensor benefits from very compact size and light weight....
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SEM micrographs of 3D printed CB-PLA samples topography after microwave treatment
Open Research DataThis dataset contains the electrochemical studies on microwave-activated carbon-black doped polylactic acid 3D printed electrodes.
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Performance‐driven modeling of compact couplers in restricted domains
PublicationFast surrogate models can play an important role in reducing the cost of EM-driven design closure of miniaturized microwave components. Unfortunately, construction of such models is challenging due to curse of dimensionality and wide range of geometry parameters that need to be included in order to make it practically useful. In this letter, a novel approach to design-oriented modeling of compact couplers is presented. Our method...
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Efficient Multi-Fidelity Design Optimization of Microwave Filters Using Adjoint Sensitivity
PublicationA simple and robust algorithm for computationally efficient design optimiza-tion of microwave filters is presented. Our approach exploits a trust-region (TR)-based algorithm that utilizes linear approximation of the filter response obtained using adjoint sensitivity. The algorithm is sequentially executed on a family of electromagnetic (EM)-simulated models of different fidelities, starting from a coarse-discretization one, and...
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Influence of dopants on structure of polycrystalline bismuth niobate
PublicationBismuth niobate (BiNbO4) has attracted attention as a low-fired ceramics with promising microwave application potential. BiNbO4 ceramics was fabricated by mixed oxide method and sintered at temperature T<1000˚C. As the sintering aids a small amount of CuO oxide was used. The crystalline structure of the ceramic samples was examined by X-ray diffraction method at room temperature. The Rietveld refinement method was used for analysis...
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Salicylaldimine-based receptor as a material for iron(III) selective optical sensing
Publicationα,α-Bis(salicylimino)-m-xylene (L) was prepared using both conventional and microwave-assisted procedure. The compound exhibits ability to colorimetric recognition of iron(III) ions in aqueous environment, what is shown by significant color change from yellow to purple. In DMSO : water (9:1 v/v) solvent system receptor creates with iron(III) cations complexes of 2:1 stoichiometry (L:Fe3+) with stability constant (log K) 7.54±0.21....
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Local mesh morphing technique for parametrized macromodels in the finite element method
PublicationThis paper presents a novel approach for enhancing the efficiency of the design process of microwave devices by means of the finite element method. It combines mesh morphing with local model order reduction (MOR) and yields parametrized macromodels that can be used to significantly reduce the number of variables in the FEM system of equations and acceleration of computer simulation. A projection basis for local reduction is generated...
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Nested Kriging Surrogates for Rapid Multi-Objective Optimization of Compact Microwave Components
PublicationA procedure for rapid EM-based multi-objective optimization of compact microwave components is presented. Our methodology employs a recently developed nested kriging modelling to identify the search space region containing the Pareto-optimal designs, and to construct a fast surrogate model. The latter permits determination of the initial Pareto set, further refined using a separate surrogate-assisted process. As an illustration,...
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Low-cost multi-criterial design optimization of compact microwave passives using constrained surrogates and dimensionality reduction
PublicationDesign of contemporary microwave circuits is a challenging task. Typically, it has to take into account several performance requirements and constraints. The design objectives are often conflicting and their simultaneous improvement may not be possible; instead, compromise solutions are to be sought. Representative examples are miniaturized microwave passives where reduction of the circuit size has a detrimental effect on its electrical...
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ZnO-decorated green-synthesized multi-doped carbon dots from Chlorella pyrenoidosa for sustainable photocatalytic carbamazepine degradation
PublicationThe promising green synthesis of carbon dots (CDs) from microalga Chlorella pyrenoidosa was achieved using simple hydrothermal and microwave-assisted methods. Doping of nanomaterials by nonmetals (N, S, and P) was confirmed by X-ray photoelectron spectroscopy (XPS), while the existence of metals in the CDs was confirmed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and transmission electron microscopy (TEM),...
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Review of Recent Advancement on Nature/Bio-inspired Antenna Designs
PublicationThis article presents an extensive examination of antennas rooted in nature and biology, showcasing their remarkable performance across a wide spectrum of frequencies—from microwave to terahertz. The limitations of traditional antenna design have become increasingly evident in the face of burgeoning demands for novel communication technologies. Conventional analytical-equation-based approaches struggle to deliver the combined performance...
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Designing a High-sensitivity Microscale Triple-band Biosensor based on Terahertz MTMs to provide a perfect absorber for Non-Melanoma Skin Cancer diagnostic
PublicationNon-melanoma skin cancer (NMSC) is among the most prevalent forms of cancer originating in the top layer of the skin, with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being its primary categories. While both types are highly treatable, the success of treatment hinges on early diagnosis. Early-stage NMSC detection can be achieved through clinical examination, typically involving visual inspection. An alternative,...
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On Decision-Making Strategies for Improved-Reliability Size Reduction of Microwave Passives: Intermittent Correction of Equality Constraints and Adaptive Handling of Inequality Constraints
PublicationDesign optimization of passive microwave components is an intricate process, especially if the primary objective is a reduction of the physical size of the structure. The latter has become an important design consideration for a growing number of modern applications (mobile communications, wearable/implantable devices, internet of things), where miniaturization is imperative due to a limited space allocated for the electronic circuitry....
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On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
PublicationThe role of numerical optimization has been continuously growing in the design of high-frequency structures, including microwave and antenna components. At the same time, accurate evaluation of electrical characteristics necessitates full-wave electromagnetic (EM) analysis, which is CPU intensive, especially for complex systems. As rigorous optimization routines involve repetitive EM simulations, the associated cost may be significant....
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Rapid and Reliable Re-Design of Miniaturized Microwave Passives by Means of Concurrent Parameter Scaling and Intermittent Local Tuning
PublicationRe-design of microwave passive components for the assumed operating frequencies or substrate parameters is an important yet a tedious process. It requires simultaneous tuning of relevant circuit variables, often over broad ranges thereof, to ensure satisfactory performance of the system. If the operating conditions at the available design are distant from the intended ones, local optimization is typically insufficient, whereas...
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Estimation of Broadband Complex Permeability Using SIW Cavity-Based Multimodal Approach
PublicationIn this article, an attractive multimodal substrate integrated waveguide (SIW) based methodology is presented for the characterization of magnetic materials in the broadband microwave frequency. The proposed approach employs a modified feed under-coupled SIW cavity instead of conventional feed over-coupled multiple SIW cavities; it uses the modified closedform expression, developed from the first principle to consider the effect...
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A Novel Synthesis Technique for Microwave Bandpass Filters with Frequency-Dependent Couplings
PublicationThis paper presents a novel synthesis technique for microwave bandpass filters with frequency-dependent couplings. The proposed method is based on the systematic extraction of a dispersive coupling coefficient using an optimization technique based on the zeros and poles of scattering parameters representing two coupled resonators.The application of this method of synthesis is illustrated using two examples involving four and five-pole...
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Developments in Green Chromatography
PublicationGreen analytical chemistry is a widely recognized concept that has led to the development of new analytical methods with reduced environmental impact and minimized analyst occupational exposure. Achievements include the development of microextraction, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) techniques. Research towards greener separation processes focuses on the elimination of toxic solvents...
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Effect of microwave and convection heating on selected nutrients of human milk
PublicationThe aim of this study was to determine the influence of the microwave heating method (MWH) on selected determinants of the nutritional value of human milk (HM) and compare to the effect exerted by the standard convection heating (CH) method, including holder pasteurization (HoP). It was showed that using MWH under conditions assumed to ensure microbiological safety, changes in the level of the nutrients were not observed. In these...
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Nitrogen-Doped Diamond Film for Optical Investigation of Hemoglobin Concentration
PublicationIn this work we present the fabrication and characterization of a diamond film which can be utilized in the construction of optical sensors for the investigation of biological samples. We produced a nitrogen-doped diamond (NDD) film using a microwave plasma enhanced chemical vapor deposition (MWPECVD) system. The NDD film was investigated with the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman...
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Doped Nanocrystalline Diamond Films as Reflective Layers for Fiber-Optic Sensors of Refractive Index of Liquids
PublicationThis paper reports the application of doped nanocrystalline diamond (NCD) films—nitrogen-doped NCD and boron-doped NCD—as reflective surfaces in an interferometric sensor of refractive index dedicated to the measurements of liquids. The sensor is constructed as a Fabry–Pérot interferometer, working in the reflective mode. The diamond films were deposited on silicon substrates by a microwave plasma enhanced chemical vapor deposition...
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Application of thin diamond films in low-coherence fiber-optic Fabry Pérot displacement sensor
PublicationThe novel fiber-optic low coherence sensor with thin diamond films is demonstrated. The undoped and boron-doped diamond films were elaborated by the use of the microwave plasma enhanced chemical vapor deposition (μPE CVD) system. The optical signal from the Fabry–Pérot cavity made with the application of those thin films is sensitive to displacement. The sensor characterization was made in the range of 0–600 μm. The measurements...
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Size Reduction of Microwave Couplers by EM-Driven Optimization
PublicationThis work addresses simulation-driven design optimization of compact microwave couplers that explicitly aims at circuit footprint area reduction. The penalty function approach allows us to minimize the area of the circuit while ensuring a proper power division between the output ports and providing a sufficient bandwidth with respect to return loss and isolation around the operating frequency. Computational cost of the optimization...
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Linear antenna microwave chemical vapour deposition of diamond films on long-period fiber gratings for bio-sensing applications
PublicationThe growth processes of nanocrystalline diamond (NCD) thin films on fused silica optical fibers with UV-induced long-period gratings (LPGs) were investigated with regard to biosensing applications. The films were deposited using a linear antenna microwave plasma enhanced chemical vapor deposition system, which allows for the growth of diamond at temperatures below 350°C. The films exhibited a high refractive index n = 2.32, as...
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Diamond Structures for Tuning of the Finesse Coefficient of Photonic Devices
PublicationFinesse coefficient is one of the most important parameters describing the properties of a resonant cavity. In this research, a mathematical investigation of the application of diamond structures in a fiber-optic Fabry–Perot measurement head to assess their impact on the finesse coefficient is proposed. We present modeled transmission functions of cavities utilizing a nitrogen-doped diamond, a boron-doped diamond, nanocrystalline...
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Performance-Driven Surrogate Modeling of High-Frequency Structures
PublicationThe development of modern high-frequency structures, including microwave and antenna components, heavily relies on full-wave electromagnetic (EM) simulation models. Notwithstanding, EM-driven design entails considerable computational expenses. This is especially troublesome when solving tasks that require massive EM analyzes, parametric optimization and uncertainty quantification be-ing representative examples. The employment of...
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Design centering of compact microwave components using response features and trust regions
PublicationFabrication tolerances, as well as uncertainties of other kinds, e.g., concerning material parameters or operating conditions, are detrimental to the performance of microwave circuits. Mitigating their impact requires accounting for possible parameter deviations already at the design stage. This involves optimization of appropriately defined statistical figures of merit such as yield. Alt-hough important, robust (or tolerance-aware)...
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Recent Advances in Accelerated Multi-Objective Design of High-Frequency Structures using Knowledge-Based Constrained Modeling Approach
PublicationDesign automation, including reliable optimization of engineering systems, is of paramount importance for both academia and industry. This includes the design of high-frequency structures (antennas, microwave circuits, integrated photonic components), where the appropriate adjustment of geometry and material parameters is crucial to meet stringent performance requirements dictated by practical applications. Realistic design has...
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A novel microstrip dual-layer rat-race coupler with compact size and enhanced bandwidth
PublicationMicrowave hybrid couplers are crucial components of mixers, phase shifters, amplifiers and other high-frequency systems. Conventional couplers are characterized by large size which limits their usefulness in modern applications. In this work, a novel compact rat-race coupler with enhanced bandwidth has been proposed. The structure consists of six compact microstrip resonant cells. It is implemented on two separate layers which permits...
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Rapid surrogate-assisted statistical analysis of compact microstrip couplers
PublicationIn this paper, a technique for low-cost statistical analysis and yield estimation of compact microwave couplers has been presented. The analysis is executed at the level of a fast surrogate model representing selected characteristic points of the coupler response that are critical to determine satisfaction/violation of the prescribed design specifications. Because of less nonlinear dependence of the characteristic points on geometry...
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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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Integrated controller for ultra high frequency technique laboratory
PublicationDepartment of Microwave and Antenna Engineering decided to modernize the laboratory of Ultra High Frequency Techniques. The main change was to replace measurement of the field distribution inside rectangular waveguides by analysing the fields around striplines. This involved the need to overcome several technical and conceptual problems. Precise positioning of the probe and reading the field distribution near the stripline is important...
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Charge-based deep level transient spectroscopy of B-doped and undoped polycrystalline diamond films
PublicationThe undoped and B-doped polycrystalline diamond thin film was synthesized by hot filament chemical vapor deposition and microwave plasma, respectively. The structural characterization was performed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The electrical properties of synthesized diamond layer were characterized by dc-conductivity method and charge deep level transient spectroscopy. The B-doped...
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RAMAN DIAGNOSTICS OF CVD DIAMOND GROWTH
PublicationDevelopment of Raman spectroscopic system for diagnostics of growth of diamond and BDD (Boron- Doped-Diamond) thin films during μPA CVD (Microwave Plasma Assisted Chemical Vapour Deposition) process is described. Raman studies of such films were carried out as in-situ monitoring of film deposition as ex-situ measurements conducted for a sample outside the reaction vessel after manufacturing process. Modular system for the in-situ...
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Carnivorous plants used for green synthesis of silver nanoparticles with broad-spectrum antimicrobial activity
PublicationIn this study, we exploit the anti-oxidative potential of four carnivorous plants to produce uniform and biologically active silver nanoparticles. The use of polyvinylpyrrolidone promoted syn-thesis of quasi-spherical nanoparticles characterized by stability and high uniformity. Their activity was tested against three human pathogens and three species of plant pathogenic bacteria. The study demonstrates the influence of synthesis...
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1,3,4-Thiadiazole-based diamides: Synthesis and complexation properties
PublicationAromatic diamides, derivative of 2,6-pyridinedicarboxylic acid and isophthalic acid, bearing 1,3,4-thiadiazole residue were prepared with satisfactory yields in conventional procedures and microwave stimulated reactions. X-ray structure of N,N-bis (1,3,4-thiadiazol-2-yl)-2,6-pyridinedicarboxamide (2) DMSO solvate (2DMSO) was described. Selective zinc(II), lanthanum(III), terbium(III) and L-tyrosine recognition was found for N,N-bis(1,3,4-thiadiazol-2-yl)-2,6-pyridinedicarboxamide...
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Inline Microwave Filters With N+1 Transmission Zeros Generated by Frequency-Variant Couplings: Coupling-Matrix-Based Synthesis and Design
PublicationA general coupling-matrix-based synthesis methodology for inline Nth-order microwave bandpass filters (BPFs) with frequency-variant reactive-type couplings that generate N+1 transmission zeros (TZs) is presented in this brief. The proposed approach exploits the formulation of the synthesis problem as three inverse nonlinear eigenvalue problems (INEVPs) so that the coupling matrix is built from their sets of eigenvalues. For this...
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Highly sensitive microwave sensors based on open complementary square split-ring resonator for sensing liquid materials
PublicationThis paper presents high-sensitivity sensors based on open complementary square split-ring resonator and modified open complementary split-ring resonator operating at 4.5 GHz and 3.4 GHz, respectively. The sensors are designed for the detection of multiple liquid materials, including distilled water, methanol, and ethanol. The liquid under test is filled in a glass container loaded using a pipette. Compared to the conventional...
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Luiza Leszkowska mgr inż.
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Inverse surrogate models for fast geometry scaling of miniaturized dual-band couplers
PublicationRe-design of microwave structures for various sets of performance specifications is a challenging task, particularly for compact components where considerable electromagnetic (EM) cross-couplings make the relationships between geometry parameters and the structure responses complex. Here, we address geometry scaling of miniaturized dual-band couplers by means of inverse surrogate modeling. Our approach allows for fast estimation...