Author: "Ala Sharaiha" - Searchworks@Jio Institute Digital Library Search Results

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280 results on '"Ala Sharaiha"'

1. A Global Optimization Method for Wideband and Small Supergain Arrays Design Using Artificial Neural Network

Author: Abdellah Touhami, Sylvain Collardey, and Ala Sharaiha
Subjects: Superdirective array, supergain array, parasitic array, directivity, artificial neural network, optimization algorithm, Telecommunication, TK5101-6720
Abstract: This paper introduces an efficient approach for compact, wideband and supergain arrays design using artificial neural network (ANN) based optimization. The proposed method optimize at the same time the distance inter-elements of the array antenna, its input impedance as well as its directivity. Such global optimization considerably improves the performances of superdirective arrays in terms of gain, bandwidth and efficiency. The proposed method is used afterwards to synthesize a three-elements array using two different unit elements. The comparison of the achieved performances and the Harrington limit reveals that the developed antennas can be qualified as supergain antennas. To our knowledge, this is the first demonstration of a wideband supergain array with more than two elements in the open literature. To validate the results, a prototype was manufactured and measured. The measurements show that the antenna has a wide impedance bandwidth of 22.6%, a peak directivity of 8.3 dBi and a total efficiency greater than 80%.
Published: 2023
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2. Monopole Antenna Miniaturization with Magneto-Dielectric Material Loading Combined with Metal Parasitic Element

Author: Thomas Finet, Ala Sharaiha, Anne-Claude Tarot, Philippe Pouliguen, Patrick Potier, and Cyrille Le Meins
Subjects: magneto-dielectric material, planar monopole antenna, miniaturization, VHF frequency band, electrically small antenna, Dynamic and structural geology, QE500-639.5
Abstract: In this paper is shown a new way to use Magneto-Dielectric Materials (MDM) in order to miniaturize monopole antennas. It is proposed to load an antenna with MDM to use the relative permeability to achieve the first 17% miniaturization rate. Then, in order to achieve better miniaturization, it is proposed to add metal parasitic plates on both sides of the material to use the relative permittivity to ensure capacitance useful to shift the antenna’s resonant frequency. By combining material loading, metallic plates’ capacitances and matching circuit designed with the real frequency technic, an antenna’s frequency shift from 350 MHz to 200 MHz is achieved corresponding to 43% of height reduction. A matching circuit has been designed to match the antenna at −5 dB. The obtained frequency bandwidth is 15% (185–215 MHz) with a realized gain of over −2.5 dBi.
Published: 2022
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3. Electrically Small Wideband Monopole Antenna Partially Loaded with Low Loss Magneto-Dielectric Material

Author: Aladdin Kabalan, Ala Sharaiha, and Anne-Claude Tarot
Subjects: magneto-dielectric materials, planar monopole antenna, miniaturization, Dynamic and structural geology, QE500-639.5
Abstract: A miniaturized new topology of the planar monopole antenna using a Magneto-Dielectric Material (MDM) is proposed in this paper. The antenna element is realized by introducing slots partially covered by the MDM. We optimized and modified the MDM topology and dimensions to enhance the impact of this material on the planar monopole antenna, including slots in its structure. This new monopole shows a miniaturization rate of 60% of the antenna’s height (51 cm antenna’s height is miniaturized to 20 cm) by covering only 5% of the antenna surface by the MDM. The measured results show the antenna’s central working frequency of 130 MHz, while the bandwidth is 30% using a broadband matching circuit using the Real Frequency Technique (RFT).
Published: 2022
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4. Compact Bandwidth Enhanced Cavity-Backed Magneto-Electric Dipole Antenna with Outer Γ-Shaped Probe for GNSS Bands

Author: Alexandre Causse, Kevin Rodriguez, Loïc Bernard, Ala Sharaiha, and Sylvain Collardey
Subjects: magneto-electric, miniature, cavity-backed antenna, GNSS, wideband, Chemical technology, TP1-1185
Abstract: In this paper, a wideband small cavity-backed magneto-electric (ME) antenna is proposed. This antenna is linearly polarized and designed to cover all the Global Navigation Satellite System (GNSS) bands. It exhibits small external dimensions of 90 × 90 × 40 mm3 (0.34 × 0.34 × 0.15 λ3 at lowest frequency) and achieves a wide impedance bandwidth of 40.5% (from 1.14 to 1.72 GHz) due to the excitation of a third resonance of the ME structure. It also provides a regular broadside gain of 5.2 dBi and stable radiation pattern in both E and H planes of the antenna.
Published: 2021
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5. Long Carbon Fibers for Microwave Absorption: Effect of Fiber Length on Absorption Frequency Band

Author: Hanadi Breiss, Aicha El Assal, Ratiba Benzerga, Chloé Méjean, and Ala Sharaiha
Subjects: lightweight epoxy foam, carbon fibers, absorbing composite, fiber length, dielectric properties, microwave absorber, Mechanical engineering and machinery, TJ1-1570
Abstract: This work presents lightweight epoxy foams loaded with very low weight percentages (≤0.5 wt.%) of carbon fibers (CFs) with different lengths (3 mm, 6 mm, and 12 mm) as broadband microwave absorbing materials for anechoic chamber application. The effect of CF length on microwave absorption, especially on the absorption frequency band, is investigated for frequencies between 1 and 15 GHz. For the elaboration of composites, three different methods—spatula, shear mixing, and ultrasounds—are used for the dispersion of CFs. The observation of these CFs, after the dispersion step, shows a high fiber breakage rate when shear mixing is used, unlike when spatula or ultrasounds methods are used. On the other hand, the characterization of the elaborated composites highlights a correlation between the mixing methods, hence the fiber brakeage, and the measured reflection coefficient (reflection loss) of the composites. As a result, the minimum value of the reflection coefficient is shifted toward the high frequencies when the fiber breakage is observed, suggesting that short CFs absorb at high frequencies while long CFs absorb at low frequencies. Dielectric properties, extracted from the measurement in free space, of composites elaborated with different fiber lengths (3 mm, 6 mm, and 12 mm) confirm that short CFs (3 mm) show maximum losses at high frequencies (around 15 GHz) while long CFs (12 mm) show maximum dielectric losses at low frequencies (below 4 GHz). However, no significant variation is observed on the real part of the relative permittivity, as a function of fiber length, for these porous composites loaded with very low CF rates. A hybrid composite, with a mix of different CF lengths, is prepared and characterized. The simulation of the absorption performance of a pyramidal absorber, based on this hybrid composite, is compared to the one of pyramidal absorber based on composites loaded with a single length of carbon fibers. The pyramidal absorber-based hybrid composite predicts the best absorption performance, especially at the low frequency band. The simulated reflection coefficient of this absorber is less than −12 dB in all the studied frequency range, and less than −40 dB for frequencies higher than 3 GHz. This result confirms the interest of using a mix of carbon fiber lengths to achieve a broadband microwave absorber.
Published: 2020
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6. Toward an Ultra-Wideband Hybrid Metamaterial Based Microwave Absorber

Author: Aicha El Assal, Hanadi Breiss, Ratiba Benzerga, Ala Sharaiha, Akil Jrad, and Ali Harmouch
Subjects: hybrid absorber, metamaterial, dielectric layer, ultra-wideband absorber, anechoic chamber, Mechanical engineering and machinery, TJ1-1570
Abstract: In this paper, we propose a novel design of an ultra-wideband hybrid microwave absorber operating in the frequency range between 2 GHz and 18 GHz. This proposed hybrid absorber is composed of two different layers that integrate a multiband metamaterial absorber and a lossy dielectric layer. The metamaterial absorber consists of a periodic pattern that is composed of an arrangement of different scales of coupled resonators and a metallic ground plane, and the dielectric layer is made of epoxy foam composite loaded with low weight percentage (0.075 wt.%) of 12 mm length carbon fibers. The numerical results show a largely expanded absorption bandwidth that ranges from 2.6 GHz to 18 GHz with incident angles between 0° and 45° and for both transverse electric and transverse magnetic waves. The measurements confirm that absorption of this hybrid based metamaterial absorber exceeds 90% within the above-mentioned frequency range and it may reach an absorption rate of 99% for certain frequency ranges. The proposed idea offers a further step in developing new electromagnetic absorbers, which will impact a broad range of applications.
Published: 2020
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7. Design of Optimized Cylindrical Structural Antenna with Quasi Length Insensitivity using CMA

Author: Raphaël, Notter, primary, Sylvain, Collardey, additional, Ala, Sharaiha, additional, Loïc, Bernard, additional, Philippe, Pouliguen, additional, and Paul, Karmann, additional
Published: 2024
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8. A multi‐objective optimisation for compact wideband and efficient superdirective antenna arrays design using network characteristic modes

Author: Abdellah Touhami, Sylvain Collardey, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), French National Research Agency (ANR) [ANR-19-CE24-0010], and ANR-19-CE24-0010,COMET-5G,Système COMpact d'Antenne Pour PassErelle DomesTique 5G(2019)
Subjects: [SPI]Engineering Sciences [physics], antenna arrays, antenna radiation patterns, directive antennas, Electrical and Electronic Engineering, modal analysis
Abstract: International audience; This paper introduces a procedure for multi-objective optimisation, for compact wideband superdirective antenna array design, using network characteristic modes. The two main objectives considered are the maximisation of the directivity in the end-fire direction, simultaneously with the minimisation of the input reflection coefficient in a large bandwidth. The proposed method is used thereafter for designing a three-element superdirective small Yagi antenna, with an overall dimensions of 0.4 lambda x 0.37 lambda x 0.18 lambda. The length of this mini yagi antenna is 60% shorter than a classical one, with the same performances of gain and bandwidth. The measured results show that the antenna bandwidth, maximum gain, and efficiency are of 11.2%, 8 dBi, and 95% respectively.
Published: 2023

9. Multi-band metamaterial-inspired half-loop antenna.

Author: Esthelladi Ramanandraibe, Mohamed Latrach, and Ala Sharaiha
Published: 2014
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10. Metamaterial-inspired high directive half-loop antenna.

Author: Esthelladi Ramanandraibe, Mohamed Latrach, and Ala Sharaiha
Published: 2014
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11. High gain design of small axial mode helical antenna over a cylindrical cavity for RFID applications.

Author: N. Rimbault, Ala Sharaiha, and Sylvain Collardey
Published: 2012
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12. Structural and photoelectrochemical properties of SrTaO2N oxynitride thin films deposited by reactive magnetron sputtering

Author: L. Le Gendre, Franck Tessier, François Cheviré, Kazuhiro Takanabe, Ahmed Ziani, Mohamad Haydoura, C. Le Paven, Ratiba Benzerga, Florent Marlec, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), King Abdullah University of Science and Technology (KAUST), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), Conseil Départemental des Alpes MaritimesMinistère de l'Education Nationale, de l'Enseignement Supérieur et de la Recherche, MESREuropean Commission, ECEuropean Regional Development Fund, FEDER, Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Reactive magnetron, Materials science, Carrier life time, European Regional Development Fund, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Engineering physics, Photo electrochemical cell, Oxynitride, Sputtering, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, media_common.cataloged_instance, Christian ministry, Thin film, European union, 0210 nano-technology, Crystallinity, Films, media_common
Abstract: International audience; In this study, the influence of the degree of crystallization and thickness of films was correlated with the photoelectrochemical performance of SrTaO2N semiconductor films for O2 evolution reaction under visible light irradiation. Oxynitride films were deposited on various substrates using the sputtering in Ar + N2 reactive atmosphere from a home-made SrTaO2N target. Films with stoichiometric composition were obtained at a high temperature (TS =800 °C) with reduced bandgap. The different substrates led to diverse degrees of film crystallization, from weakly crystallized to fully c-axis oriented. The photoelectrochemical performance was improved by improving the film crystallinity and the thickness. For further improvement of the photoelectrochemical performance, the following three limiting factors are identified 1) low absorption coefficient, especially in the visible domain from 500 to 600 nm; 2) short lifetimes of excited charge carriers; and 3) permittivity with only moderate values lower than 10 in the visible-light domain.
Published: 2020

13. Thermal oxidation of oxynitride films as a strategy to achieve (Sr2Ta2O7)100-x(La2Ti2O7)x based oxide perovskite films with x = 1.65

Author: François Cheviré, C. Le Paven, A. Moréac, Ratiba Benzerga, L. Le Gendre, Florent Marlec, Franck Tessier, Ala Sharaiha, Mohamad Haydoura, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Ministère de l'Education Nationale, de l'Enseignement Superieur et de la Recherche, European Union through the European Regional Development Fund, Brittany Région and Côtes d’Armor Département, Conseil Départemental des Côtes d’Armor, Saint Brieuc Armor Agglomération, Syndicat de Gestion du Pole Universitaire de Saint Brieuc, Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS]Physics [physics], 010302 applied physics, Thermal oxidation, Materials science, Analytical chemistry, Oxide, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Dielectric, Sputter deposition, Tungsten, 021001 nanoscience & nanotechnology, 01 natural sciences, chemistry.chemical_compound, chemistry, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, [CHIM]Chemical Sciences, Thin film, 0210 nano-technology, Perovskite (structure), Solid solution
Abstract: International audience; This study concerns STLTO compounds of the ferroelectric (Sr 2 Ta 2 O 7) 100-x (La 2 Ti 2 O 7) x solid solution. The purpose is to produce the STLTO composition x = 1.65 as thin films by thermal oxidation of the corresponding oxynitride composition. Indeed, the combination of an STLTO oxide target with a dioxygen-rich reactive atmosphere during the sputtering deposition leads to Sr-deficient oxide thin films, shifting composition and structure from the perovskite to the tetragonal tungsten bronze type. An alternative synthesis pathway is to first deposit, under nitrogen-rich atmosphere, stoichiometric oxynitride films and produce, by thermal annealing under air, the stoichiometric oxide. For low oxidation temperatures ([550-600°C]), samples remain intact and display an oxide character but still contain a significant amount of nitrogen; they could be described as intermediate phases containing nitrogen-nitrogen pairs as demonstrated by Raman. Dielectric characteristics of these original film materials are of interest with a tunability value of 26 % at 30 kV/cm (10 kHz).
Published: 2020

14. Design of an End-Fire Efficient Superdirective Electrically Small Antenna Array

Author: Abdellah Touhami, Sylvain Collardey, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), French National Research Agency (ANR) [ANR-19-CE24-0010], and ANR-19-CE24-0010,COMET-5G,Système COMpact d'Antenne Pour PassErelle DomesTique 5G(2019)
Subjects: [SPI]Engineering Sciences [physics], parasitic array, Electrically small antenna, Efficiency, Superdirective array
Abstract: International audience; This paper presents the design of an efficient end-fire parasitic superdirective array based on an electrically small antenna (ESA) (ka approximate to 1). The unit element is internally loaded with two inductances. With those loads the antenna exhibits an impedance bandwidth of 11 % with a radiation efficiency greater than 96 % in the whole frequency band of interest. The ESA based superdirective array achieves a maximal end-fire directivity of 9.3 dB at 780 MHz with a radiation efficiency greater than 80% To validate the simulation results, a prototype was fabricated and measured. The measurement are in a good agreement with simulation.
Published: 2022

15. Design and Development of a Tunable Ferroelectric Microwave Surface Mounted Device

Author: Caroline Borderon, Hartmut Gundel, Kevin Nadaud, Ala Sharaiha, Raphaël Renoud, Abdullah Haskou, Stéphane Ginestar, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), French National Research Agency (ANR) in the frame of the Project SENSAS, Nantes Université (NU)-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Permittivity, Materials science, Acoustics and Ultrasonics, Ferroelectric devices, 01 natural sciences, law.invention, agility, [SPI]Engineering Sciences [physics], law, 0103 physical sciences, Electrical and Electronic Engineering, 010301 acoustics, Instrumentation, business.industry, tunable antenna, article, Biasing, Ferroelectric applications, Ferroelectricity, Capacitor, microwave radiation, Optoelectronics, Dielectric loss, Radio frequency, business, Decoupling (electronics), Microwave
Abstract: International audience; Based on a BaSrTiO ferroelectric thin film, a discrete tunable surface mounted device (SMD) capacitor has been developed for microwave frequency applications. The proposed SMD topology has the particular advantage of inherent decoupling between the RF signal and the dc biasing voltage, necessary to tune the ferroelectric permittivity. The design and technological development of the SMD component is presented, and the synthesis of the ferroelectric thin film is summarized. Material characterization shows convenient tunability, while low dielectric losses at 10 MHz. The integration of the SMD tunable capacitor into a Planar Inverted-F Antenna has been done in order to evaluate the agility and tunability performance of the antenna.
Published: 2020

16. Design and optimization of ultra-wideband planar multilayer absorber based on long-carbon fiber-loaded composites

Author: Hanadi Breiss, Aicha El Assal, Ala Sharaiha, Ratiba Benzerga, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Union through the European Regional Development FundEuropean Commission, Ministry of Higher Education and Research, Brittany Region, Cotes d'Armor Departement and Saint Brieuc Armor Agglomeration through the CPER Projects MATECOM and SOPHIE-STICC., Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Materials science, Multilayer absorber, Microwave absorption, 02 engineering and technology, [SPI]Engineering Sciences [physics], Planar, 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, Composite material, Reflection coefficient, Absorption (electromagnetic radiation), Electrical impedance, Mechanical Engineering, 020206 networking & telecommunications, Epoxy, 021001 nanoscience & nanotechnology, Carbon fiber based composites, Mechanics of Materials, visual_art, Solid mechanics, visual_art.visual_art_medium, Génetic algorithm, 0210 nano-technology, Layer (electronics), Anechoic chamber, Microwave
Abstract: International audience; This article presents a strategy for designing optimal microwave planar multilayer absorbers based on epoxy foam composites loaded with carbon fibers of 12 mm length. Firstly, the impedance gradient principle (gradual loaded composites) was adopted to realize two multilayer absorbers, of 125 mm thickness, using slightly loaded composites (0.0125 wt% < CFs < 0.075 wt%) and relative highly loaded composites (0 wt% < CFs < 0.4 wt%), respectively. The simulation of these absorbers shows that composites with very low CF rates are sufficient to achieve a very close absorption performance and bandwidth to that of the commercial absorber, in the entire studied frequency range (0.75-18 GHz). Secondly, the genetic algorithm optimizer is used to achieve a multilayer absorber that presents the best compromise between absorption performance and thickness. Different CF-loaded composites and layer thicknesses are therefore tested; a multilayer absorber with a total thickness of 98 mm is then proposed. This absorber shows a better reflection coefficient and a better compromise (absorption/total thickness) than that of the commercial absorber, while presenting a reduction of 22% in thickness. The presented simulation and measurement results confirm that a judicious choice of the composition and the thickness of each layer is necessary to optimize the absorption performance of a planar multilayer absorber. This paper also shows the advantage of using an optimizer to improve the absorption performance while reducing the total thickness of the absorber.
Published: 2021

17. Network Characteristic Modes Approach to Design Reactively Loaded Parasitic Superdirective Arrays

Author: Abdellah Touhami, Ala Sharaiha, and Sylvain Collardey
Published: 2021

18. Low Profile Multiband Magnetoelectric Antenna for GNSS and Telemetry

Author: Alexandre Causse, Loic Bernard, Ala Sharaiha, and Sylvain Collardey
Published: 2021

19. Low profile folded monopole antenna higly miniaturized by the use of low loss magnetodielectic materials in the VHF frequency band

Author: Thomas Finet, Ala Sharaiha, Anne-Claude Tarot, Philippe Pouliguen, Patrick Potier, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut d'Electronique et de Télécommunications de Rennes (IETR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Centre National de la Recherche Scientifique (CNRS), Délégation générale de l'armement (DGA), and Ministère de la Défense
Subjects: [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2021

20. Ultra-Wideband Hybrid Based Metamaterial Absorber

Author: Akil Jrad, Ali Harmouch, A. El Assal, Ala Sharaiha, Ratiba Benzerga, and Hanadi Breiss
Subjects: Materials science, business.industry, Metamaterial, Ultra-wideband, Epoxy, Resonator, visual_art, Metamaterial absorber, visual_art.visual_art_medium, Optoelectronics, Dielectric loss, Hybrid material, Absorption (electromagnetic radiation), business
Abstract: In this paper, we propose a multi-resonance MM design which will be used for the realization of an ultra-wideband hybrid microwave absorber. The metamaterial absorber consists of a symmetrical structure, called V-shape, with different scales of coupled resonators and the hybrid absorber is carried out by the association of this metamaterial to a lossy dielectric layer, made of epoxy foam composite loaded with low weight percentage (0.075 wt.%) of 12 mm length carbon fibers. The simulation and measurement results of the hybrid material of 16.2 mm thickness show an absorption bandwidth between 2.6 GHz and 18 GHz for both normal and oblique incidences.
Published: 2021

21. Artificial Neural Network Synthesis Based Approach For Superdirective Antenna Arrays Design

Author: Sylvain Collardey, Abdellah Touhami, and Ala Sharaiha
Subjects: Novel technique, Artificial neural network, Computer science, Radial basis function neural, Acoustics, Antenna (radio), Directivity, Monopole antenna, Network model
Abstract: In this work, a novel technique is proposed to design superdirective antenna arrays using artificial neural network (ANN). A radial basis function neural network model (RBNN) is developed and used to determine the optimal inter-elements separating distance and its corresponding excitation coefficients for a single frequency. The developed model is deployed for designing a three stacked S-shaped monopole antenna array. The simulation result show that a maximal directivity of 10 dBi for a separation distance of 0.16 λ, was achieved.
Published: 2021

22. Parametric Optimization of a Non-Foster Circuit Embedded in an Electrically Small Antenna for Wideband and Efficient Performance

Author: Ala Sharaiha, Hussein Jaafar, Dominique Lemur, Sylvain Collardey, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Regional Development Fund, Ministry of Higher Education and Research, Brittany and Rennes Métropole through the Contrat de Plan Etat Region (CPER) Project SOPHIE/STIC and Ondes, Direction Général de l’Armement, Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: non-foster matching, Computer science, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Bandwidth (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, 020206 networking & telecommunications, 02 engineering and technology, 7. Clean energy, Capacitance, miniaturization, [SPI]Engineering Sciences [physics], Electrically small antenna, 0202 electrical engineering, electronic engineering, information engineering, Electronic engineering, Miniaturization, ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS, Electrically small atenna, Electrical and Electronic Engineering, Wideband, Electrical impedance, Monopole antenna, Computer Science::Information Theory, Negative impedance converter
Abstract: International audience; In this paper, we present the design of a small, wideband antenna with an embedded non-Foster circuit. The design procedure is based on modeling the antenna in the presence of the EM model of the negative impedance converter (NIC) and trying to optimize the components and location of this active circuit inside the antenna. The EM modeling of the circuit provides the possibility to identify the key parameters that mostly affect the performance of the antenna in terms of bandwidth and efficiency. These parameters are then optimized accordingly. This procedure is applied on a monopole antenna, which has its natural resonance at 2.2 GHz. With an embedded non-Foster circuit, the antenna is miniaturized to cover wideband frequencies around 900 MHz. Two examples are considered for different NIC topologies, after optimizing the components of the NIC, the best performance was given by the second antenna, which exhibits an impedance bandwidth of 50% (0.84-1.45 GHz) and total efficiency of 25%. The measurement results of both antennas are in good agreement with simulations showing a significant enhancement with respect to the passive antenna.
Published: 2019

23. Characteristic Modes Approach to Design Compact Superdirective Array With Enhanced Bandwidth

Author: Sylvain Collardey, Hussein Jaafar, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Ministry of Higher Education and Research, Brittany and Rennes Métropole through the CPER Project SOPHIE/STIC & Ondes, Direction Général de l’Armement, Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: 010302 applied physics, Physics, Compact antennas, Acoustics, Bandwidth (signal processing), 020206 networking & telecommunications, 02 engineering and technology, 01 natural sciences, Directivity, Narrow bandwidth, network characteristic modes (NCMs), [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Modal, Multiple frequency, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, Wideband, multiport antennas, Electrical impedance, Excitation, superdirectivity
Abstract: International audience; Superdirective arrays have become the key technique in enhancing the directivity of electrically small antennas. By forming an array of closely spaced unit elements, a high directivity can be achieved. Despite the high directivity, these arrays suffer from narrow bandwidth and low efficiency. In this paper, we present an approach to enhance the bandwidth of superdirective arrays using the network characteristic modes. The key step is to use an internally loaded compact wideband unit element. The loads inside the unit element are used to manipulate the characteristic modes in order to optimize its impedance bandwidth. A two-element endfire array is then formed. The modal coefficients of the characteristic fields are then optimized at multiple frequency points in order to radiate a maximal directivity in the endfire direction. The best current excitation that can maintain a constant directivity as a function of frequency is then deduced. Finally, a feeding network that can provide the desired excitation at the array ports is designed and integrated on the array system, where the 1 dB directivity bandwidth is about 23% with Dmax=7.1 dBi. The antenna impedance bandwidth is equal to 15%.
Published: 2018

24. Compact bandwidth enhanced cavity-backed magneto-electric dipole antenna with outer Γ-shaped probe for gnss bands

Author: Sylvain Collardey, Alexandre Causse, Loic Bernard, Ala Sharaiha, Kevin Rodriguez, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut franco-allemand de recherches de Saint-Louis (ISL), DGA-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Franco-Allemand de Recherches de Saint-Louis, ISL, Jonchère, Laurent, Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), DGA-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: [SPI] Engineering Sciences [physics], TP1-1185, 02 engineering and technology, 7. Clean energy, Biochemistry, Analytical Chemistry, Radiation pattern, [SPI]Engineering Sciences [physics], Optics, 0202 electrical engineering, electronic engineering, information engineering, Bandwidth (computing), Electrical and Electronic Engineering, Wideband, Instrumentation, Miniature, Physics, GNSS, business.industry, Linear polarization, Chemical technology, Communication, 020208 electrical & electronic engineering, Resonance, 020206 networking & telecommunications, Atomic and Molecular Physics, and Optics, Dipole, GNSS applications, Cavity-backed antenna, Antenna (radio), business, Magneto-electric
Abstract: International audience; In this paper, a wideband small cavity-backed magneto-electric (ME) antenna is proposed. This antenna is linearly polarized and designed to cover all the Global Navigation Satellite System (GNSS) bands. It exhibits small external dimensions of 90 × 90 × 40 mm3 (0.34 × 0.34 × 0.15 λ3 at lowest frequency) and achieves a wide impedance bandwidth of 40.5% (from 1.14 to 1.72 GHz) due to the excitation of a third resonance of the ME structure. It also provides a regular broadside gain of 5.2 dBi and stable radiation pattern in both E and H planes of the antenna. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Published: 2021

25. Deposition and dielectric characterization of perovskite and ttb oxide thin films of the (Sr,La)-(Ta,Ti)-O system

Author: Mohamad Haydoura, Claire Le Paven-Thivet, Ratiba Benzerga, Laurent LE GENDRE, Xavier Castel, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Castel, Xavier, and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, [SPI.NANO] Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.MAT] Engineering Sciences [physics]/Materials, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2021

26. Small CP Cavity-Backed Magneto-Electric Antenna with parasitic elements for GNSS Applications

Author: Loic Bernard, Alexandre Causse, Sylvain Collardey, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut franco-allemand de recherches de Saint-Louis (ISL), DGA-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), DGA-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: electormagnetidcs, 02 engineering and technology, 7. Clean energy, [SPI]Engineering Sciences [physics], Optics, propagation, 0202 electrical engineering, electronic engineering, information engineering, Magneto, Miniature, Physics, GNSS, Magneto-Electric, business.industry, Axial ratio, 020208 electrical & electronic engineering, Resonance, 020206 networking & telecommunications, GNSS applications, Wideband, cavity-backed antenna, Multi-band device, measurements, Antenna (radio), antennas, business, Broadside
Abstract: International audience; In this paper a small dual-band cavity-backed magnetoelectric (ME) antenna is proposed. This antenna is circularly polarized (CP) and designed to operate in all GNSS bands (1.164 - 1.30 GHz and 1.559 - 1.61GHz). Parasitic elements are added to create additional resonance. It exhibits axial ratio (AR) < 1.3dB in all the considered bands and small external dimensions of 90x90x37.5 mm3 (0.346x0.346x0.144 λ3 at lowest frequency). It also provides a regular broadside gain of 5.2 dBic. © 2021 EurAAP.
Published: 2021

27. Ultra-porous and lightweight microwave absorber based on epoxy foam loaded with long carbon fibers

Author: Hanadi Breiss, Ali Harmouch, Ala Sharaiha, Ratiba Benzerga, Aicha El Assal, Akil Jrad, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université Libanaise, Ministère de l'Education Nationale, de l'Enseignement Superieur et de la Recherche, MESREuropean Commission, ECEuropean Regional Development Fund, FEDER, Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)
Subjects: Absorption (acoustics), Materials science, Composite absorber, Composite number, 02 engineering and technology, Dielectric, 010402 general chemistry, 01 natural sciences, [SPI]Engineering Sciences [physics], Carbon fibers, General Materials Science, Composite material, Reflection coefficient, Porosity, Lightweight epoxy foam, Mechanical Engineering, Epoxy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Solvent, Mechanics of Materials, visual_art, Dielectric properties, visual_art.visual_art_medium, Microwave absorber, 0210 nano-technology, Microwave
Abstract: International audience; A simple methodology to fabricate ultra-porous and lightweight epoxy foam composites loaded with carbon fibers is presented. These materials are proposed for microwave absorbing application. The elaborated composite density can be controlled via proper proportioning of carbon fiber/solvent/surfactant/epoxy components constituting the absorber composites. The influence of the weight percentage of these different components, on the composite structure, is studied. The density of the composites can be reduced to 0.05g‧cm−3 while the density of the neat epoxy foam is about 0.12g‧cm−3. Dielectric characterization of composites elaborated with low weight percentages of carbon fibers (from 0.0125 wt.% to 0.075 wt.%) is conducted using free space method. The simulation of a multilayer absorber is conducted and predicts a promising absorption performance (reflection coefficient andlt;-10 dB) for the wide studied frequency band; this result was confirmed by the measurement of a multilayer absorber prototype. Finally, these performances are compared to commercial absorber materials having same dimensions. © 2020 Elsevier Ltd
Published: 2021

28. A Technique for Including Edge Diffraction Effects on RCS Evaluation at Fresnel Region Ranges

Author: Ala Sharaiha, Razvan D. Tamas, Ilie Valentin Mihai, University Politehnica of Bucharest [Romania] (UPB), Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Constanta Maritime University [Roumania] (CMU), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: Diffraction, Physics, Radar cross-section, Field (physics), business.industry, equivalent currents, 020208 electrical & electronic engineering, Extrapolation, Measure (physics), Physics::Optics, 020206 networking & telecommunications, 02 engineering and technology, Physical optics, physical optics, [SPI]Engineering Sciences [physics], Optics, 0202 electrical engineering, electronic engineering, information engineering, Scattering parameters, Tangent space, radar cross section, business, Fresnel region
Abstract: International audience; The aim of this paper is to propose a simple and low-cost technique to measure the RCS of a complex target in the Fresnel region and in a multipath environment. The diffracted field by the target is calculated using a method based on equivalent currents. The reflected field is computed using the physical optics approach and the tangent plane approximation. The ratio between the analytical expression of the radar cross section in the far-field and Fresnel region results in a field-zone extrapolation factor for the diffracted field. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that field-zone extrapolation factor. The method was validated by simulations and measurements on a rectangular, metallic target. © 2020 EurAAP.
Published: 2020

29. A modified physical optics approach for extrapolating fresnel region RCS measurements at high incidence angles

Author: Ilie Valentin Mihai, Razvan D. Tamas, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Constanta Maritime University [Roumania] (CMU), Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii, UEFISCDI, Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU)
Subjects: Diffraction, Physics, Radar cross-section, Field (physics), business.industry, Uniform theory of diffraction, Extrapolation, Physics::Optics, 020206 networking & telecommunications, 02 engineering and technology, Radar cross section, Physical optics, [SPI]Engineering Sciences [physics], Optics, 0202 electrical engineering, electronic engineering, information engineering, Scattering parameters, business, Fresnel region, Incidence (geometry)
Abstract: International audience; The aim of this paper is to extend the application area of the physical optics for RCS measurements at Fresnel region antenna-to-target distances and incidence angles higher than 20° by taking into account the field diffracted by the target edges. The diffracted field is calculated by using an approach based on equivalent currents with diffraction coefficients resulting from the uniform theory of diffraction. The ratio between the analytical expression of the radar cross section at far-field and Fresnel regions results in an extrapolation factor for the diffracted field. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that extrapolation factor. The experimental validation of the proposed technique demonstrates reasonable agreement with the simulations. © 2020 IEEE.
Published: 2020

30. Carbon Fibers Loaded Composites for Microwave Absorbing Application: Effect of Fiber Length and Dispersion Process on Dielectric Properties

Author: Mathieu Badard, A. El Assal, Ratiba Benzerga, Ala Sharaiha, C. Le Paven, Chloé Mejean, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Union through the European Regional Development Fund (ERDF)European Union (EU), Ministry of Higher Education and ResearchMinistry of Higher Education and Scientific Research (MHESR), Region BretagneRegion Bretagne, Departement des Cotes d'ArmorRegion Bretagne, Saint-Brieuc Armor Agglomeration, through the CPER Project 2015-2020 MATECOM, Saint-Brieuc Armor Agglomeration, through the CPER Project 2015-2020 SOPHIE/STIC Ondes, Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: Permittivity, Materials science, [SDV]Life Sciences [q-bio], Composite number, 02 engineering and technology, Dielectric, 01 natural sciences, 0103 physical sciences, carbon fibers, Materials Chemistry, Electrical and Electronic Engineering, Composite material, 010302 applied physics, Reflection loss, Carbon black, Epoxy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Absorber composites, dielectric properties, visual_art, visual_art.visual_art_medium, fiber dispersion, Dielectric loss, 0210 nano-technology, Microwave
Abstract: International audience; In this work, a new composite for microwave absorption applications, especially for anechoic chambers, is studied. We propose to substitute carbon black loaded polyurethane foam, currently used in commercial absorbers, by epoxy foam filled with carbon fibers. The purpose of the present paper is to study the influence of three dispersion methods (spatula, shear mixer and ultrasound probe) and four fiber lengths (1 mm, 3 mm, 6 mm and 12 mm) on the homogeneity and dielectric properties (permittivity epsilon ' and dielectric losses tan delta) of achieved composites. Long fibers dispersed with spatula have shown higher dielectric properties than short fibers. However, such a soft dispersion method was revealed to be inefficient to disperse properly the long fibers. Although a homogenous dispersion was obtained with the shear mixer (mechanical dispersion), we noticed an important degradation of the fibers which lead to a decrease of the dielectric properties. Dispersion with ultrasounds appears to be a good compromise between homogeneity and dielectric properties of composites. Finally, electromagnetic simulation predicted a high absorption performance for pyramidal absorber made with the 12 mm-carbon fibers loaded composite with reflection loss lower than - 50 dB for frequencies ranging between 8 GHz and 18 GHz.
Published: 2020

31. Long Carbon Fibers for Microwave Absorption: Effect of Fiber Length on Absorption Frequency Band

Author: Aicha El Assal, Ala Sharaiha, Chloé Mejean, Hanadi Breiss, Ratiba Benzerga, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Union through the European Regional Development Fund (ERDF) European Union (EU), Ministry of Higher Education and Research, Brittany Region, Cotes d'Armor Departement, Saint Brieuc Armor Agglomeration through the CPER Project MATECOM, Saint Brieuc Armor Agglomeration through the CPER Project SOPHIE-STICC, Syndicat de Gestion du Pole Universitaire de Saint Brieuc (France), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, fiber length, lcsh:Mechanical engineering and machinery, Relative permittivity, 02 engineering and technology, Dielectric, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Article, [SPI]Engineering Sciences [physics], Dispersion (optics), carbon fibers, lcsh:TJ1-1570, Fiber, Electrical and Electronic Engineering, Reflection coefficient, Composite material, absorbing composite, Absorption (electromagnetic radiation), microwave absorber, Mechanical Engineering, Reflection loss, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Control and Systems Engineering, lightweight epoxy foam, dielectric properties, 0210 nano-technology, Microwave
Abstract: This work presents lightweight epoxy foams loaded with very low weight percentages (&le, 0.5 wt.%) of carbon fibers (CFs) with different lengths (3 mm, 6 mm, and 12 mm) as broadband microwave absorbing materials for anechoic chamber application. The effect of CF length on microwave absorption, especially on the absorption frequency band, is investigated for frequencies between 1 and 15 GHz. For the elaboration of composites, three different methods&mdash, spatula, shear mixing, and ultrasounds&mdash, are used for the dispersion of CFs. The observation of these CFs, after the dispersion step, shows a high fiber breakage rate when shear mixing is used, unlike when spatula or ultrasounds methods are used. On the other hand, the characterization of the elaborated composites highlights a correlation between the mixing methods, hence the fiber brakeage, and the measured reflection coefficient (reflection loss) of the composites. As a result, the minimum value of the reflection coefficient is shifted toward the high frequencies when the fiber breakage is observed, suggesting that short CFs absorb at high frequencies while long CFs absorb at low frequencies. Dielectric properties, extracted from the measurement in free space, of composites elaborated with different fiber lengths (3 mm, 6 mm, and 12 mm) confirm that short CFs (3 mm) show maximum losses at high frequencies (around 15 GHz) while long CFs (12 mm) show maximum dielectric losses at low frequencies (below 4 GHz). However, no significant variation is observed on the real part of the relative permittivity, as a function of fiber length, for these porous composites loaded with very low CF rates. A hybrid composite, with a mix of different CF lengths, is prepared and characterized. The simulation of the absorption performance of a pyramidal absorber, based on this hybrid composite, is compared to the one of pyramidal absorber based on composites loaded with a single length of carbon fibers. The pyramidal absorber-based hybrid composite predicts the best absorption performance, especially at the low frequency band. The simulated reflection coefficient of this absorber is less than &minus, 12 dB in all the studied frequency range, and less than &minus, 40 dB for frequencies higher than 3 GHz. This result confirms the interest of using a mix of carbon fiber lengths to achieve a broadband microwave absorber.
Published: 2020

32. Characterization of ferrite tunability at microwave frequencies: Application to VHF tunable antennas

Author: Anne-Claude Tarot, Jean-Luc Mattei, Alexis Chevalier, Christophe Delaveaud, Vassidiki Doumouva, Aladdin Kabalan, Ala Sharaiha, Vincent Laur, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Mines-Télécom [Paris] (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Materials science, business.industry, Frequency band, Characterization, 020208 electrical & electronic engineering, Ferrite, 020206 networking & telecommunications, 02 engineering and technology, Magnetostatics, Permeability, Spectral line, [SPI]Engineering Sciences [physics], Antenna, Permeability (electromagnetism), 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Ferrite (magnet), Coaxial line, business, Microwave
Abstract: International audience; A microwave characterization method that allows extracting permeability variations of ferrite as a function of applied static magnetic field is presented. This method is based on a coaxial line method for which a calibration technique is proposed to take into account the variations of the bias system. Measured permeability spectra are used to design a tunable antenna in VHF frequency band. © 2019 IEEE.
Published: 2019

33. Ferroelectricity and high tunability in novel strontium and tantalum based layered perovskite materials

Author: Franck Tessier, Thibault Dufay, Claire Le Paven, Ratiba Benzerga, Florent Marlec, François Cheviré, Laurent Le Gendre, Bachir Messaid, Ala Sharaiha, Benoit Guiffard, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), European Union, Ministry of Higher Education and Research, Brittany Région, Côtes d’Armor Département, Saint Brieuc Agglomération and the Syndicat de Gestion du Pole Universitaire de Saint Brieuc (France), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Permittivity, Materials science, Tantalum, Relative permittivity, chemistry.chemical_element, 02 engineering and technology, Perovskite, 01 natural sciences, Electric field, Lattice (order), 0103 physical sciences, Materials Chemistry, La2Ti2O7, 010302 applied physics, Condensed matter physics, Tunability, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Ferroelectricity, chemistry, Sr2Ta2O7, Ceramics and Composites, Dielectric loss, 0210 nano-technology, Ferroelectric, Solid solution
Abstract: International audience; The present study reveals the ferroelectric nature of the novel (Sr2Ta2O7)100-x(La2Ti2O7)x layered perovskite materials and highlights a large variation of their permittivity under electric fields associated with very low dielectric loss in the radio-frequency range. More precisely, an ideal solid solution has been evidenced within the composition range 0 ≤ x ≤ 5 with lattice parameters and cell volume varying linearly with x. The relative permittivity also depends on the composition and reaches a maximum value (365 @10 kHz, RT), associated with a high tunability (17.6% @0.38 kV/mm) with very low dielectric loss lower than 2.10−3. Variation of the relative permittivity as a function of the temperature is also demonstrated, with the existence of a temperature maximum, increasing with the composition. Polarization-electric field (P-E) measurements feature hysteresis loops for compositions x ≥ 1.85, in conjunction with current peaks in the I-E curves originating from ferroelectric domains switching.
Published: 2018

34. A reconfigurable miniaturized planar inverted-F antenna with integrated BaSrTiO3 capacitor

Author: Stéphane Ginestar, Hartmut Gundel, Ala Sharaiha, Raphaël Renoud, Sylvain Collardey, Caroline Borderon, and Abdullah Haskou
Subjects: Materials science, business.industry, Planar inverted f antenna, 020206 networking & telecommunications, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Capacitor, law, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Electrical and Electronic Engineering, 0210 nano-technology, business
Published: 2018

35. Small Wide-Band Printed Inverted-L Antenna with Non-Foster Matching

Author: Ala Sharaiha, Sylvain Collardey, Abdullah Haskou, Dominique Lemur, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: Matching (statistics), Coaxial antenna, Computer Networks and Communications, Computer science, Acoustics, 020208 electrical & electronic engineering, 020206 networking & telecommunications, 02 engineering and technology, [SPI.TRON]Engineering Sciences [physics]/Electronics, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Electrically small antenna, Microstrip antenna, 0202 electrical engineering, electronic engineering, information engineering, Miniaturization, Wide band, Electrical and Electronic Engineering, Antenna (radio), ComputingMilieux_MISCELLANEOUS, Software
Abstract: International audience
Published: 2018

36. Tunable TTB strontium and tantalum based thin films: Influence of the deposition parameters on the structural and dielectric properties

Author: François Cheviré, L. Le Gendre, R. Seveno, C. Le Paven, Florent Marlec, Ratiba Benzerga, Franck Tessier, Ala Sharaiha, Mohamad Haydoura, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)
Subjects: 010302 applied physics, Strontium, Materials science, Analytical chemistry, Tantalum, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Chemistry, Dielectric, Tungsten, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Tetragonal crystal system, chemistry, Sputtering, 0103 physical sciences, [CHIM]Chemical Sciences, General Materials Science, Dielectric loss, Thin film, 0210 nano-technology
Abstract: International audience; Structural and dielectric properties of thin films produced by reactive radiofrequency sputtering of a (Sr2Ta2O7)100-x (La2Ti2O7)x target with x = 1.65 were studied. The chemical composition characterization shows Sr/Ta ratios ranging between 0.49 and 0.56, thus pointing out the deposition of strontium deficient films, belonging to the tetragonal tungsten bronze family. The highest permittivities and tunabilities, associated with the lowest dielectric losses, are obtained when films are pure and fully textured. This is achieved for a 900 nm-thick film deposited at TS = 850 °C: ε’ = 116, tanδ = 0.007 and tunability T = 14.5% at 340 kV/cm and 100 kHz.
Published: 2021

37. Perovskite (Sr2Ta2O7)100−x(La2Ti2O7)x ceramics: From dielectric characterization to dielectric resonator antenna applications

Author: C. Le Paven, Ratiba Benzerga, Vincent Laur, Ala Sharaiha, Mohamad Haydoura, François Cheviré, L. Le Gendre, Franck Tessier, Alexis Chevalier, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Equipe Smart Materials and Related Technologies (Lab-STICC_SMART), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Université de Brest (UBO), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes 1 (UR1), Institut Mines-Télécom [Paris] (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-Institut Mines-Télécom [Paris] (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL), Université de Rennes 1 (UR1), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Permittivity, Ceramics, Dielectric resonator antenna, Materials science, 02 engineering and technology, Dielectric, 010402 general chemistry, 01 natural sciences, Resonator, Materials Chemistry, [CHIM]Chemical Sciences, business.industry, Mechanical Engineering, Ferroelectric ceramics, Metals and Alloys, [CHIM.MATE]Chemical Sciences/Material chemistry, Dielectric resonator, 021001 nanoscience & nanotechnology, Ferroelectricity, 0104 chemical sciences, Mechanics of Materials, Dielectric properties, Perovskite materials, Optoelectronics, Dielectric loss, 0210 nano-technology, business
Abstract: International audience; In this paper, ferroelectric ceramics with (Sr2Ta2O7)100−x(La2Ti2O7)x (STLTO) compositions have been investigated and their dielectric properties have been characterized in wide frequency band (from few kHz to few GHz); their integration in Dielectric Resonator Antennas (DRA) was conducted. The dense STLTO ceramics have been obtained by high temperature sintering of powders synthetized by solid state chemistry route. STLTO crystalline cell parameters and volume vary linearly as a function of the chemical composition (x) thus demonstrating an ideal solid solution domain for 0 ≤ x ≤ 3. Dielectric characterizations highlight that the permittivity and the dielectric loss vary according to the composition (x) and that the lowest losses are obtained for x < 1.65 compositions. The latter corresponds to the transition between the ferroelectric and paraelectric compositions of the STLTO material at room temperature. A low profile DRA structure was realized using a cylindrical paraelectric STLTO resonator (with x = 0) with a permittivity of 83 and losses tanδ = 5 ×10⁻³ @ 3.3 GHz. The DRA prototype was simulated, produced and tested. It exhibits a hybrid HEM11δ mode, with a resonant frequency at 5.80 GHz, a 4.9% bandwidth and a gain of 6.4 dB. These features confirm the potential of the paraelectric STLTO compositions in compact antennas radiating at frequencies below 6 GHz.
Published: 2021

38. Radar Cross Section of a Slightly Tilted Disk in the Fresnel Region and Real Environment

Author: Ala Sharaiha, Razvan D. Tamas, Ilie Valentin Mihai, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Constanta Maritime University [Roumania] (CMU), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU)
Subjects: Physics, Radar cross-section, Field (physics), business.industry, 020208 electrical & electronic engineering, Horn antenna system, Physics::Optics, 020206 networking & telecommunications, Near and far field, 02 engineering and technology, Radius, Radar cross section, Physical optics, Oblique incidence, [SPI]Engineering Sciences [physics], Optics, Transformation (function), Disk, 0202 electrical engineering, electronic engineering, information engineering, Scattering parameters, Antenna (radio), business, Fresnel region
Abstract: International audience; This paper presents a method to measure the radar cross section of a disk (with known radius) at normal and oblique incidence in the Fresnel region and real environment. The proposed method relies both on the physical optics approach and averaging the field distribution over the transmitting and receiving antenna apertures. The ratio between the analytical expression of the radar cross section at far-field and Fresnel region results in a transformation factor between both field zones. The RCS obtained through scattering parameters measured at Fresnel region distances is corrected with the analytical transformation factor previously determined. The measurements are in a good agreement with simulations and theoretical far field radar cross section at normal and oblique incidence. © 2019 IEEE.
Published: 2019

39. A Technique for Radar Cross Section Measurements in the Fresnel Region

Author: Ilie Valentin Mihai, Ala Sharaiha, Razvan D. Tamas, University Politehnica of Bucharest [Romania] (UPB), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU), PN-III-P1-1.2-PCCDI-2017-0404, Holistic of the impact of the renewable energy sources on the environment and climate, Romanian Executive Unit for Financing Higher Education, Research, Development and Innovation, Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Constanta Maritime University [Roumania] (CMU), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Electromagnetic field, Physics, log-periodic antenna, Radar cross-section, Anechoic chamber, radar cross section (RCS), business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, 020206 networking & telecommunications, 02 engineering and technology, [SPI]Engineering Sciences [physics], Optics, Vivaldi antenna, Inverse scattering problem, 0202 electrical engineering, electronic engineering, information engineering, Calibration, Constant current, Electrical and Electronic Engineering, Antenna (radio), business, Fresnel region, Multipath propagation, ComputingMilieux_MISCELLANEOUS, Computer Science::Information Theory
Abstract: This letter presents a novel inverse scattering method for estimating the radar cross section of a target placed in the Fresnel region of the radar antennas. By considering a constant current distribution on the transmitting antenna and a uniform illumination of the target and furthermore of the receiving antenna, the electromagnetic field is averaged over the apertures of the antennas. The hypothesis of a constant current distribution stands for ultrawideband antennas, and a quasi-uniform illumination can be assumed for ranges within the Fresnel region and for the particular case where antenna and target sizes are in the same order as the distance to the target. A calibration procedure for the measurement setup is also proposed. A validation of the method through simulations and measurements in an anechoic chamber and in a real, multipath propagation environment is provided by using two different types of antenna systems.
Published: 2019

40. Enhance the impact of the magneto-dielectric materials to miniaturize a planar monopole antenna

Author: A. Kabalan, Ala Sharaiha, A.-C. Tarot, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: Materials science, Field (physics), Low-profile antennas, High permittivity substrates, Physics::Optics, Planar monopole antenna, 02 engineering and technology, Dielectric, 7. Clean energy, Dielectric materials, [SPI]Engineering Sciences [physics], Miniaturized sizes, Magneto-dielectrics, 0202 electrical engineering, electronic engineering, information engineering, Miniaturization, Narrow bands, Magneto, Different geometry, business.industry, Monopole antennas, 020208 electrical & electronic engineering, Magnetic confinement fusion, 020206 networking & telecommunications, Antenna efficiency, Magnetic field, Optoelectronics, business
Abstract: International audience; The use of Magneto-Dielectrics Materials (MDM) is becoming increasingly popular in the development of low-profile antennas [1]-[3] as well as achieving a high miniaturized size, these Materials allows avoiding highly concentrated field confinement when using high-permittivity substrates, which results in low antenna efficiency and narrow-band operation. This document presents the miniaturization impact of different geometries of the low-loss Magneto-Dielectric Materials (MDM) [4] on the planar monopole antenna covering the VHF band. © 2019 URSI. All rights reserved.
Published: 2019

41. A comparison between Vivaldi and log-periodic antenna systems for radar cross section measurements in the Fresnel region

Author: Ala Sharaiha, Valentin Mihai, Razvan D. Tamas, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU), Sciences et Technologies de l'information et de la Communication, Université Paris-Saclay, STIC DSEuropean Commission, ECEuropean Regional Development Fund, FEDER, Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Constanta Maritime University [Roumania] (CMU), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Physics, Radar cross-section, Field (physics), Target surface, Gain measurement, Acoustics, 020208 electrical & electronic engineering, Astrophysics::Instrumentation and Methods for Astrophysics, 020206 networking & telecommunications, 02 engineering and technology, Transfer function, log-periodic antenna system, [SPI]Engineering Sciences [physics], 0202 electrical engineering, electronic engineering, information engineering, Range (statistics), radar cross section, Antenna (radio), Fresnel region, Log-periodic antenna, Computer Science::Information Theory
Abstract: International audience; The aim of this paper is to compare two types of antenna systems for radar cross section measurements on a rectangular target in a real environment and in the Fresnel region based on the field integration on the target surface. Delay of the wave propagation through the antennas influence the distance range between antenna and target. In order to reduce the effects of the propagation, a normalized, distance average of the transfer function is applied. Both theoretical concepts and practical considerations are validated, based on measurements accomplished with log-periodic and Vivaldi antennas. © 2019 IEEE.
Published: 2019

42. Influence of the substrate on the structural and photocatalytic properties of oxynitride SrTaO2N films

Author: Claire Le Paven, Laurent LE GENDRE, Ahmed Ziani, Ratiba Benzerga, Florent Marlec, Mohamad Haydoura, Franck Tessier, François Cheviré, Ala Sharaiha, Kazuhiro Takanabe, Benzerga, Ratiba, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), King Abdullah University of Science and Technology (KAUST), Institut d'Electronique et de Télécommunications de Rennes (IETR), Centre National de la Recherche Scientifique (CNRS)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics], [SPI.MAT] Engineering Sciences [physics]/Materials, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2019

43. (Sr,La)-(Ta,Ti)-O-N perovskite oxide and oxynitride films: influence of the deposition and annealing conditions on the structure and electrical properties

Author: Laurent LE GENDRE, Claire Le Paven, Mohamad Haydoura, Ratiba Benzerga, Florent Marlec, Ala Sharaiha, Franck Tessier, François Cheviré, Benzerga, Ratiba, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut d'Electronique et de Télécommunications de Rennes (IETR), Centre National de la Recherche Scientifique (CNRS)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Nantes Université (NU)-Université de Rennes 1 (UR1), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)
Subjects: [SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics], [SPI.MAT] Engineering Sciences [physics]/Materials, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2019

44. Electromagnetic multilayer absorber made of carbon fibers loaded epoxy foam

Author: Ala Sharaiha, Hanadi Breiss, A. El Assal, Ratiba Benzerga, Akil Jrad, Ali Harmouch, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut d'Electronique et de Télécommunications de Rennes (IETR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Systèmes électroniques, Télécommunications et Réseaux (Université Libanaise) (LaSTRe), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: [SPI]Engineering Sciences [physics], [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Materials science, visual_art, visual_art.visual_art_medium, Epoxy, Composite material, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract: International audience
Published: 2019

45. An UWB Physical Optics Approach for Fresnel-Zone RCS Measurements on a Complex Target at Non-Normal Incidence

Author: Ilie Valentin Mihai, Razvan D. Tamas, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), University Politehnica of Bucharest [Romania] (UPB), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: Radar cross-section, Fresnel zone, Extrapolation, 02 engineering and technology, Biochemistry, Article, Analytical Chemistry, [SPI]Engineering Sciences [physics], Optics, 0202 electrical engineering, electronic engineering, information engineering, Scattering parameters, radar cross section, fresnel region, Electrical and Electronic Engineering, Instrumentation, Physics, Coupling, business.industry, 020208 electrical & electronic engineering, 020206 networking & telecommunications, Physical optics, complex target, Atomic and Molecular Physics, and Optics, rectangular plate, non-normal incidence, Antenna (radio), business, Multipath propagation
Abstract: International audience; In this paper, we propose a fast method for measuring the radar cross section of a complex target at non-normal incidences and Fresnel region antenna-to-target distances. The proposed method relies both on the physical optics approach and on averaging the field distribution over the transmitting and receiving antenna apertures. The ratio between the analytical expression of the radar cross section at far-field and Fresnel region results in a field-zone extrapolation factor. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that field-zone extrapolation factor. The method is suitable to be used in a perturbed, multipath environment by applying the distance averaging technique, coupling subtraction or time gating. Our technique requires a very simple measuring configuration consisting of two horn antennas and a vector network analyzer. The experimental validation of the proposed technique demonstrates reasonable agreement with simulated radar cross section at non-normal incidence.
Published: 2019

46. Reflection coefficient measurements in the l-band with low directivity antennas in a multipath site

Author: Ilie Valentin Mihai, Ala Sharaiha, Liliana Anchidin, Razvan D. Tamas, Constanta Maritime University [Roumania] (CMU), University Politehnica of Bucharest [Romania] (UPB), Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii, UEFISCDI, Université de Nantes (UN)-Université de Rennes 1 (UR1), Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)
Subjects: Coupling, Physics, L band, Radar cross-section, low-directivity antennas, Acoustics, microwave reflection coefficient, 020206 networking & telecommunications, 02 engineering and technology, Directivity, Radiation pattern, L-band, [SPI]Engineering Sciences [physics], Horn (acoustic), 0202 electrical engineering, electronic engineering, information engineering, distance averaging method, Reflection coefficient, Multipath propagation, Computer Science::Information Theory
Abstract: International audience; Reflection coefficient measurements can be performed by using two antennas and a material under test sample of a known radar cross section. At frequencies in the L-band high-directivity antennas such as horn antennas would have large physical size. In this work, we propose a method for measuring the reflection coefficient based on planar, low-directivity antennas. Although they are smaller than horn antennas corrections concerning the effect of the mutual proximity on the mutual coupling and on the global radiation pattern should be taken into account. We also propose a new version of our distance averaging method adapted to radar-type configurations in order to measure the reflection coefficient in a multipath site. Our approach was validated by measurements on a rectangular aluminum plate. © 2018 IEEE.
Published: 2018

47. The effect of the antenna group delay on RCS measurements in the L-band

Author: Ala Sharaiha, Razvan D. Tamas, Liliana Anchidin, Ilie Valentin Mihai, University Politehnica of Bucharest [Romania] (UPB), Constanta Maritime University [Roumania] (CMU), Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii, UEFISCDI, Université de Nantes (UN)-Université de Rennes 1 (UR1), Universitatea Maritimă Constanta = Constanta Maritime University = Université Maritime de Constanta [Roumania] (CMU), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Coupling, L band, Radar cross-section, delay, Acoustics, time domain, 020208 electrical & electronic engineering, 020206 networking & telecommunications, 02 engineering and technology, [SPI]Engineering Sciences [physics], Horn (acoustic), 0202 electrical engineering, electronic engineering, information engineering, Range (statistics), radar cross section, Antenna (radio), S-parameters, Impulse response, Group delay and phase delay
Abstract: International audience; When measuring the radar cross section (RCS) at a distance in the same order as the antennas and the target sizes the range should be accurately assessed. In the L-band the use of highly directive antennas such as horn antennas is restricted by the size they would have. We propose therefore to use a pair of log-periodic arrays instead although they are less directive and supposed to exhibit a stronger mutual coupling. A differential technique based on subtracting the impulse response with and without target is also proposed. The method was successfully validated on a rectangular target. © 2018 IEEE.
Published: 2018

48. Wideband Electrically Small Antenna Internally Loaded With Non-Foster Circuit

Author: Ala Sharaiha, Hussein Jaafar, Dominique Lemur, Sylvain Collardey, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Union through the European Regional Development Fund (ERDF), Ministry of Higher Education and Research, Brittany, Rennes Metropole, through the CPER Project SOPHIE / STIC Ondes, Direction General de l'Armement (DGA), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Physics, Acoustics, Bandwidth (signal processing), Reactance, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, 020206 networking & telecommunications, 02 engineering and technology, Data_CODINGANDINFORMATIONTHEORY, Non-Foster reactance, law.invention, Electrically small antenna, [SPI]Engineering Sciences [physics], law, Hardware_GENERAL, ComputerApplications_MISCELLANEOUS, 0202 electrical engineering, electronic engineering, information engineering, ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS, Dipole antenna, Active antenna, Wideband, Internal matching, Electrical impedance, Negative impedance converter
Abstract: International audience; This paper presents the design of a wideband electrically small antenna using internally loaded Non-Foster circuit. The negative capacitance provided by the circuit can significantly compensate the high reactance of the antenna and match it in a wide bandwidth. However in order to accurately predict the behaviour of the active antenna, the EM model of the non-foster circuit is taken into account in the full wave simulation of the antenna. The loaded antenna having an electrical size ka = 0.3 is matched in a wideband (34%).
Published: 2018

49. Equivalent circuit for an ultra-wide bande monopole antenna inserted in a magneto-dielectric medium

Author: Ala Sharaiha, A.-C. Tarot, A. Kabalan, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), French National Research Agency (ANR) as part of the project MISTRAL, competitiveness cluster 'Images et reseaux', Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Physics, Lossless compression, Monopole, Equivalent circuit, business.industry, Magnetic monopole, Physics::Optics, Hardware_PERFORMANCEANDRELIABILITY, Dielectric, [SPI]Engineering Sciences [physics], Computer Science::Hardware Architecture, Computer Science::Emerging Technologies, Optics, UWB, Magneto-dielectric, Broadband, Hardware_INTEGRATEDCIRCUITS, RLC circuit, business, Magneto, Monopole antenna, Hardware_LOGICDESIGN
Abstract: International audience; An equivalent circuit for a wide-band monopole antenna inserted in an infinite lossless Magneto-Dielectric Medium (MDM) has been developed, from its equivalent circuit in the air which consists of N RLC parallels. The equivalent circuit is sufficiently accurate for a broadband simulation comparing the simulated data obtained from a full-wave simulations.
Published: 2018

50. Ferroelectricity and high tunability in novel strontium and tantalum based layered perovskite materials

Author: Florent Marlec, Claire Le Paven, Laurent LE GENDRE, Ratiba Benzerga, François Cheviré, Franck Tessier, Benoit Guiffard, Ala Sharaiha, Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Université de Nantes (UN)-Université de Rennes 1 (UR1), and Le Gendre, Laurent
Subjects: [CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract: International audience; The present study concerns the achievement of new layered-type perovskite ferroelectrics materials with a Curie temperature tailored to be at ambient temperature. This was achieved by mixing two ferroelectrics (Sr2Ta2O7 (STO), TC = -107°C, and La2Ti2O7 (LTO), TC = 1461°C) in a (Sr2Ta2O7)100-x(La2Ti2O7)x solid solution. Composition (x) was varied between 0 and 5 and led to an ideal solid solution with an evolution of the lattice parameters and cell volume following the Vegard's law. The dielectric characterization has shown that both relative permittivity (k) and dielectric loss (tand) are stable in frequency from 1 to 100 kHz. At RT and fixed frequency, the relative permittivity increases then decreases with the composition (x); a maximum (k = 365) is reached for x = 1.65 (@10 kHz). Permittivity also peaks for a temperature (TM) shifting towards higher values with the amount of La2Ti2O7 (x) in the solid solution; compositions with x ≥ 1.85 have a TM higher than room temperature. Polarization-electric field (P-E) measurements have highlighted non-open loops for the compositions x = 0 and 1.65, while hysteresis were obtained for x = 1.85, 2.0, 2.5 and 3.0, along with switching current peaks in I-E, thus confirming that these compositions are ferroelectrics at RT. The variation of the relative permittivity as a function of a DC electric field (i.e. tunability) was demonstrated for x ≥ 1.5. A very high tunability (17.6 % @0.38 kV/mm; 10 kHz) was obtained for the composition x = 1.65, associated with very low dielectric losses (tand < 2.10-3). These new and high level performances make (Sr2Ta2O7)100-x(La2Ti2O7)x promising lead-free ferroelectric materials which can compete with standard ferroelectrics.
Published: 2018

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