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Realization of ultrasmall scale electromechanical materials has been promising for advanced functional devices. Recently, single-atom devices have been proposed as the ultimate miniaturization of functional devices beyond the nanoscale; however, achieving an atomic-scale local electromechanical response is still challenging due to physical size limitation of electromechanical properties as well as technical difficulties in fabricating the functional materials in a single atom precision. Here, we demonstrate a non-trivial negative electromechanical response at an oxygen vacancy in paraelectric BaHfO₃ using first-principles finite electric field calculations. We find an electrostrictive response at the vacancy site in the same order of magnitude in well-known oxide materials. Surprisingly, we also discover an unusual “negative” sign of electrostriction in the oxygen vacancy. The detailed electronic structure analysis demonstrates that a unique electric field response of a localized defect electronic structure is the origin of this negative electrostriction of vacancy. The present results provide an important implication for the design of ultra-small electromechanical functions at an atomic scale.

The flexoelectric effect, coupling polarization and strain gradient as well as strain and electric field gradients, is universal to dielectrics, but, as compared to piezoelectricity, it is more difficult to harness as it requires field gradients and it is a small-scale effect. This drawback can be overcome by suitably designing multiscale metamaterials made of a non-piezoelectric base material but exhibiting apparent piezoelectricity. We develop a theoretical and computational framework to perform topology optimization of the representative volume element of such metamaterials by accurately modeling the governing equations of flexoelectricity using a Cartesian B-spline method, describing geometry with a level set, and resorting to genetic algorithms for optimization. We consider a multi-objective optimization problem where area fraction competes with each one of the four fundamental piezoelectric functionalities (stress/strain sensor/actuator). We computationally obtain Pareto fronts, and discuss the different geometries depending on the apparent piezoelectric coefficient being optimized. Our results show that optimal material architectures strongly depend on the specific functional property being optimized, and that, except for stress actuators, optimal structures are low-area-fraction lattices. In general, we find competitive estimations of apparent piezoelectricity as compared to reference materials such as quartz and PZT ceramics. This opens the possibility to design devices for sensing, actuation and energy harvesting from a much wider, cheaper and effective class of materials., Peer Reviewed, Postprint (published version)

This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides (PPWs). With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristics, the planar Mikaelian lens antennas are easy to fabricate and integrate into standard planar feeds. A numerical computation of the ray paths based on Snell's law describes the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far-field of the lens antenna. The information on far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and a significant reduction in computation resources and times., QC 20240412

This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides. With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristic, the planar Mikaelian lens antennas are easy to fabricate and integrate to standard planar feeds. A numerical computation of the ray paths based on the Snell’s law gives a description of the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far field of the lens antenna. The information of far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and significant reduction in computation resources and times.

This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides. With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristic, the planar Mikaelian lens antennas are easy to fabricate and integrate to standard planar feeds. A numerical computation of the ray paths based on the Snell’s law gives a description of the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far field of the lens antenna. The information of far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and significant reduction in computation resources and times.

In this contribution, we propose the use of the multimodal transfer matrix approach to investigate two-dimensional dielectric and magnetic periodic structures that possess glide symmetries. This method allows for the calculation of the attenuation constant in bandgaps, leaky structures, and material losses. In addition, this method enables a fundamental understanding of the operation of periodic structures. The method is also used to explain the differential response produced by dielectric/magnetic glide symmetries., Part of ISBN 978-88-31299-07-7QC 20230911

Non-destructive material measurements for structural analysis of building elements are a valuable tool in situations where invasive techniques are unfeasible. In this work, a free-space penetration loss measurement technique is applied to the study of wall structure, relying on educated guesses about the internal composition of the material under test (MUT). Using a setup with antennas and a vector network analyzer (VNA), the sample's transmission coefficients are captured in the 1-18 GHz frequency range and compared to the loss model presented in the ITU-R (International Telecommunication Union-Radiocommunication Sector) Recommendation. Tests are run in a laboratory environment on three wood samples, and in the field on two internal partitions of a standard office building in Finland. The method's limitations and operation are assessed in terms of root mean squared error (RMSE), and the results allow for detection of material anomalies and discontinuities and a general understanding of the MUT's electrical behavior., Las medidas no destructivas para el análisis estructural de elementos de construcción representan una herramienta valiosa en situaciones donde las técnicas invasivas son inviables. En este trabajo se aplica una técnica de medición de pérdidas de penetración en espacio libre al estudio estructural de paredes, basándose en suposiciones fundamentadas sobre la composición interna del material bajo estudio (MUT). Utilizando una configuración con antenas y un analizador de redes vectorial (VNA), se capturan los coeficientes de transmisión de la muestra en la banda de 1 a 18 GHz y se comparan con el modelo de pérdidas presentado en las Recomendaciones de la UIT-R (Unión Internacional de Telecomunicaciones-Sector de Radiocomunicaciones). Las pruebas se realizan en un entorno de laboratorio con tres muestras de madera, y en campo con dos tabiques internos de un edificio de oficinas estándar en Finlandia. Las limitaciones y el funcionamiento del método se evalúan en términos de error cuadrático medio de la raíz (RMSE); los resultados permiten detectar anomalías y discontinuidades del material, y comprender el comportamiento eléctrico del MUT en general., Les mesures no destructives per a l'anàlisi estructural d'elements de construcció suposen una eina valuosa en situacions on les tècniques invasives són inviables. En aquest treball s'aplica una tècnica de mesurament de pèrdues de penetració en espai lliure a l'estudi estructural de parets, basant-se en suposicions fonamentades sobre la composició interna del material sota estudi (MUT). Utilitzant una configuració amb antenes i un analitzador de xarxes vectorial (VNA), es capturen els coeficients de transmissió de la mostra en la banda de 1 a 18 GHz i es comparen amb el model de pèrdues presentat en les Recomanacions de la UIT-R (Unió Internacional de Telecomunicacions-Sector de Radiocomunications). Els tests es realitzen en un entorn de laboratori amb tres mostres de fusta, i en el camp amb dos tabics interns d'un edifici d'oficines estàndard a Finlàndia. Les limitacions i el funcionament del mètode s'avaluen en termes d'error quadràtic mitjà de l'arrel (RMSE); els resultats permeten detectar anomalies i discontinuïtats del material, i entendre el comportament elèctric del MUT en general.

Multifrequency atomic force microscopy (AFM) enhances resolving power, provides extra contrast channels, and is equipped with a formalism to quantify material properties pixel by pixel. On the other hand, multifrequency AFM lacks the ability to extract and examine the profile to validate a given force model while scanning. We propose exploiting data-driven algorithms, i.e., machine learning packages, to predict the optimum force model from the observables of multifrequency AFM pixel by pixel. This approach allows distinguishing between different phenomena and selecting a suitable force model directly from observables. We generate predictive models using simulation data. Finally, the formalism of multifrequency AFM can be employed to analytically recover material properties by inputting the right force model., Peer Reviewed, Postprint (published version)

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

This article summarizes the recently discovered opportunities of geodesic lenses for producing high-performing antennas for 5G/6G communications. First, we explain the operation of these lenses based on Geometrical Optics with rays that follow "the shortest optical path" on the geodesic surface. Also, we explain the connection between geodesic lenses and rotationally symmetric graded-index lenses. Generally, geodesic lenses can be implemented without the need of dielectric materials, resulting in very efficient devices constructed with a fully-metallic configuration. When combined with a feeding network and a radiating transition, such as a flare or a leaky wave, they can produce a multiple-beam lens antenna, of interest for applications requiring one-dimensional (e.g., azimuthal) coverage diversity such as in cell tower communication systems. Prototypes of these antennas have been recently tested, demonstrating remarkable performance in the Ka-band, part of which is considered for 5G. At high operational frequencies allocated for 5G/6G, geodesic lenses offer an opportunity to produce cost-effective antenna solutions with high directivity, high efficiency and spatial diversity through multiple beams., QC 20220309

Aperiodic stacks of dielectric low- and high-index films can be designed to enhance third-harmonic generation (THG) in reflection of near infrared laser pulses using computer optimization. Numerical and analytical results suggest that the TH energy increases rapidly with increasing number of films and the ratio of the high and low index. Our optical matrix based THG model that takes into account the full pulse bandwidth predicts conversion efficiencies of about 7% for transform-limited Gaussian pulse bandwidths of 16 nm for mirrors with 45 layers, which exceed those expected from periodic designs. Stability against film thickness fluctuations expected from the deposition process and information about laser-induced damage are components of the design process. Frequency tripling mirrors manufactured from hafnia and silica by our collaboration partners in the Laser Center in Hannover according to our designs showed maximum conversion efficiencies of about 2% for 60 fs pulses at 815 nm. The main obstacles to achieving higher conversion efficiencies in practice are undesired material modifications in the currently used dielectric materials, observed during a single pulse and pulse trains in the high-index layer.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Study of the characteristics of the different layers of the EWOD lens and the manufacturing method for each one of them. In addition, the hydrophobic or hydrophilic behavior of a liquid is studied when it is deposited on the lens and a certain voltage is applied to it. All work done in a clean room., Estudio de las características de las diferentes capas de la lente basadas en la electrohumectación del dieléctrico y el método de fabricación de cada una de ellas. Además, se estudia el comportamiento hidrofóbico o hidrofílico de un líquido cuando se deposita sobre la lente y se le aplica un determinado voltaje. Todo el trabajo realizado en una sala blanca., Estudi de les característiques de les diferents capes de la lent basades en l'electrohumectació del dielèctric i el mètode de fabricació de cadascuna. A més, s'estudia el comportament hidrofòbic o hidrofílic d'un líquid quan es diposita sobre la lent i se li aplica un voltatge determinat. Tota la feina feta en una sala blanca.

Lignin is an abundant biopolymer deriving from industrial pulping processes of lignocellulosic biomass. Despite the huge amount of yearly produced lignin waste, it finds scarce application as a fine material and is usually destined to be combusted in thermochemical plants to feed, with low efficiency, other industrial processes. So far, the use of lignin in materials science is limited by the scarce knowledge of its molecular structure and properties, depending also on its isolation method. However, lignin represents an intriguing feedstock of organic material. Here, the structural and chemical-physical characteristics of two kraft lignins, L1 and L2, are analyzed. First, several molecular characterization techniques, such as attenuated total reflectance - Fourier transform infrared spectroscopy, elemental analyses, gel permeation chromatography, evolved gas analysis-mass spectrometry, UV–vis, 31P- and 13C- nuclear magnetic resonance spectroscopies are applied to get insights into their different structures and their degree of molecular degradation. Then, their efficient application as gate dielectric materials is demonstrated for organic field-effect transistors, finding the increased capacity of L1 with respect to L2 in triggering functional and efficient devices with both p-type and n-type organic semiconductor molecules. © 2022 The Authors. Advanced Sustainable Systems published by Wiley-VCH GmbH., Università di Pisa, UniPi, This research received financial support from the University of Pisa through the project “BIHO 2021—Bando Incentivi di Ateneo Horizon e Oltre” (D.d. 408, Prot. no. 0030596/2021) and the program “Visiting Fellow.” The authors gratefully acknowledge the support and guidance of Prof. N. S. Sariciftci for this collaboration and his valuable discussions. The authors thank CISUP (Center for Instrument Sharing of the University of Pisa) for the access to the ATR?FTIR and FE?SEM facilities.

Lignin is an abundant biopolymer deriving from industrial pulping processes of lignocellulosic biomass. Despite the huge amount of yearly produced lignin waste, it finds scarce application as a fine material and is usually destined to be combusted in thermochemical plants to feed, with low efficiency, other industrial processes. So far, the use of lignin in materials science is limited by the scarce knowledge of its molecular structure and properties, depending also on its isolation method. However, lignin represents an intriguing feedstock of organic material. Here, the structural and chemical-physical characteristics of two kraft lignins, L1 and L2, are analyzed. First, several molecular characterization techniques, such as attenuated total reflectance - Fourier transform infrared spectroscopy, elemental analyses, gel permeation chromatography, evolved gas analysis-mass spectrometry, UV–vis, 31P- and 13C- nuclear magnetic resonance spectroscopies are applied to get insights into their different structures and their degree of molecular degradation. Then, their efficient application as gate dielectric materials is demonstrated for organic field-effect transistors, finding the increased capacity of L1 with respect to L2 in triggering functional and efficient devices with both p-type and n-type organic semiconductor molecules. © 2022 The Authors. Advanced Sustainable Systems published by Wiley-VCH GmbH., Università di Pisa, UniPi, This research received financial support from the University of Pisa through the project “BIHO 2021—Bando Incentivi di Ateneo Horizon e Oltre” (D.d. 408, Prot. no. 0030596/2021) and the program “Visiting Fellow.” The authors gratefully acknowledge the support and guidance of Prof. N. S. Sariciftci for this collaboration and his valuable discussions. The authors thank CISUP (Center for Instrument Sharing of the University of Pisa) for the access to the ATR?FTIR and FE?SEM facilities.

Dans ce présent travail, quatre classes de contributions sont réalisées: • Contribution à la modélisation numérique de la conduction de la chaleur, en régime transitoire, des solides multi-matériaux caractérisés par des tenseurs de conductivité thermique anisotrope et de natures différentes. L’équation de la conduction de la chaleur est exprimée par la variable température. • Contribution à la modélisation numérique de la conduction de la chaleur, en régime transitoire, des solides multi-matériaux caractérisés par des tenseurs de conductivité thermique anisotrope et de natures différentes, avec ou sans changement de phase. L’équation de la conduction de la chaleur est exprimée par la variable enthalpie volumique. • Contribution à la modélisation numérique de la conduction de la chaleur, en régime stationnaire, par la transformée de Kirchhoff : i) cas de conduction-convection et ii) cas de conduction-convection-radiation (conditions aux limite). • Contribution à la modélisation de chauffage diélectrique des biocomposites (matériaux diélectriques) anisotrope et non linéaire avec changement de phase. Dans le cas de la résolution numérique de l’équation de la conduction en fonction de la température, la méthode implicite des éléments finis est considérée. Pour l'amélioration de l'efficacité et de la précision de la solution numérique, la stratégie prédicteur/correcteur est utilisé [35]. L'approche proposée est validée pour cinq situations : 1. Distribution de la température analytique dans un cylindre anisotrope avec un transfert de chaleur convectif (avec variation circonférentielle). 2. Distribution de la température analytique dans une sphère anisotrope avec un transfert de chaleur convectif (avec variation circonférentielle). 3. Distribution de la température numérique pour une plaque carrée constituée de deux matériaux différents, dont l'un est un matériau isotrope, tandis que le second est orthotrope. 4. Chauffage anisotrope du bois (en tenant compte du changement

Aperiodic stacks of dielectric low- and high-index films can be designed to enhance third-harmonic generation (THG) in reflection of near infrared laser pulses using computer optimization. Numerical and analytical results suggest that the TH energy increases rapidly with increasing number of films and the ratio of the high and low index. Our optical matrix based THG model that takes into account the full pulse bandwidth predicts conversion efficiencies of about 7% for transform-limited Gaussian pulse bandwidths of 16 nm for mirrors with 45 layers, which exceed those expected from periodic designs. Stability against film thickness fluctuations expected from the deposition process and information about laser-induced damage are components of the design process. Frequency tripling mirrors manufactured from hafnia and silica by our collaboration partners in the Laser Center in Hannover according to our designs showed maximum conversion efficiencies of about 2% for 60 fs pulses at 815 nm. The main obstacles to achieving higher conversion efficiencies in practice are undesired material modifications in the currently used dielectric materials, observed during a single pulse and pulse trains in the high-index layer.

Depuis de nombreuses années, l'intégration monolithique sur puce a permis de fortement miniaturiser et transformer les systèmes optiques "sur table" en circuits photoniques, tout en améliorant leurs performances, en garantissant leur fiabilité opérationnelle et en réduisant les coûts de fabrication. A ce jour, les applications visées adressent massivement le domaine des télécommunications et notamment les transmissions à très haut débit. Cependant, à mesure que la technologie évolue sur ces marchés, des applications émergentes apparaissent dans des domaines à très fort potentiel comme la santé, la détection, les systèmes LIDAR ou encore l’imagerie. Par les résultats obtenus, cette thèse ambitionne de participer à cette évolution technologique en utilisant un matériau transparent dans le visible (SiON) et compatible avec les technologies de fabrication déjà existantes, pour une application d'imagerie haute résolution appelée synthèse d'ouverture et fonctionnant dans le domaine du visible. Cette dernière consiste en la mise en interférence de signaux sources afin de reconstruire l'image d'un objet. Une telle technique a la capacité d'atteindre des résolutions aussi élevées que des dispositifs très encombrants déployés pour l'astrophysique dans le domaine de l'IR, et doit pouvoir bénéficier des avantages de la miniaturisation offerte par les techniques actuelles de fabrication de la microélectronique. Toutefois, un tel projet de recherche impose de lever des verrous en termes de conception et de fabrication de briques de base (guides optiques et coupleur MMI) pour obtenir des performances compatibles avec les exigences imposées par un système complet d'imagerie opérant sur le principe de la synthèse d'ouverture. Les travaux exposés dans cette thèse, qui s’inscrivent dans ce projet de recherche, portent principalement sur la modélisation des structures réalisées qui ont permis d'optimiser leur design final, la mise au point des procédés technologiques de leur fabricatio, Since many years, monolithic on-chip integration has made it possible to strongly miniaturize and convert "Lab-made" optical systems into photonic circuits, while improving their performance, guaranteeing their operating reliability as well as reducing manufacturing costs. Nowadays, the targeted applications have massively focused on the field of telecommunications and particularly for high-rate data transmissions. However, as technology evolves in these markets, new emerging applications appear in high potential areas such as healthcare, sensing, LIDAR systems and imaging. From obtained results, this thesis aims to participate to this technological evolution by using a transparent material in the visible range (SiON) and compatible with already existing fabrication technologies, for an application of high resolution imaging called aperture synthesis and operating in the visible range. The latter consists in the interference of source signals in order to reconstruct the image of an object. Such a technique enables to reach resolution as high as very sophisticated systems deployed for astrophysics in the IR range, and must benefit from the advantages of the miniaturization offered by the techniques currently used in microelectronics. However, this project requires to overcome challenges regarding design and fabrication of building blocks (optical waveguides and MMI couplers) to obtain performance compatible with the requirements imposed by a complete aperture synthesis imaging system. These PhD works, developed in the framework of this large project, mainly report on the modeling of the addressed structures which made it possible to optimize their final design, the optimization of the technological processes for their fabrication (deposition, lithography, plasma etching), and finally the analysis of performance obtained from dedicated characterizations.

Consider the following: writing (and reading) ferroelectric memories without applying voltage;1–3 piezoelectric-like transduction without piezoelectric materials;4–6 bone remodeling7 and mammalian hearing;8,9 asymmetric fracture toughness;10 and bulk photovoltaic effects in non-polar materials.11 What do these apparently disparate phenomena have in common? Flexoelectricity.

Interconnects are the performance limiters in ULSI circuits connecting number of transistors as per Moore’s law. Performance of an Integrated Circuits is largely depending on these interconnect’s structure where wires are placed closer to each other with high aspect ratios. Today, interconnects account for a substantially bigger proportion of overall latency and expense in integrated circuits than in the past. Interconnect pitch reduction increases layout density but decreases interconnect RC delay. Increasing the metal aspect ratio (thickness/width) improves RC delay, although the best results are obtained when the aspect ratio is around 2. Adding more interconnect layers enhances density and performance, but within a few generations, practical limits are reached. To meet future ULSI connectivity standards, new conductor and dielectric materials, as well as enhanced circuit design methodologies, will be required. In this paper, the trends, challenges and solutions for scaling of interconnects are discussed for achieving high performance in ultra-deep submicron USLI circuits.

Subwavelength nanostructures with tunable compositions and geometries show favorable optical functionalities for the implementation of nanophotonic systems. Precise and versatile control of structural configurations on solid substrates is essential for their applications in on-chip devices. Here, we report all-solid-phase reconfigurable chiral nanostructures with silicon nanoparticles and nanowires as the building blocks in which the configuration and chiroptical response can be tailored on-demand by dynamic manipulation of the silicon nanoparticle. We reveal that the optical chirality originates from the handedness-dependent coupling between optical resonances of the silicon nanoparticle and the silicon nanowire via numerical simulations and coupled-mode theory analysis. Furthermore, the coexisting electric and magnetic resonances support strong enhancement of optical near-field chirality, which enables label-free enantiodiscrimination of biomolecules in single nanostructures. Our results not only provide insight into the design of functional high-index materials but also bring new strategies to develop adaptive devices for photonic and electronic applications.

The development of the Internet of Things and communication systems of the fifth generation leads to the need to place many antenna elements in a limited volume. Therefore, wearable electronics antennas are often located directly on the device body. Such surfaces can often be thought of as a conducting cylinder covered with a dielectric material. The task of analysing the radiation patterns of antennas located on such surfaces becomes urgent. This paper shows a method for analysing antenna directivity diagrams using the Green's functions method of cylindrical layered media. This method allows to obtain in an analytical form the expressions for the analysis of such structures, which makes it possible to reduce the cost of computer time in modelling. The presented results show what kind of distortions are introduced into the radiation pattern of antennas located on a cylinder compared to an antenna located on a flat surface. © 2021 Institute of Physics Publishing. All rights reserved.

[EN] In this project, the synthesis of a series of propylene copolymers with a functionalized olefin, bearing a pyrrole group, has been carried out. Olefin functionalization is a current field of study that seeks to achieve materials that, maintaining their insulating properties, can be advantageously used in energy storage devices, because of a higher permittivity value, superior thermal and mechanical stabilities or both. The synthesis has been carried out by metallocene catalysis in a certain range of compositions. Materials obtained have been characterized at the molecular level by analysing their microstructure in composition and configuration, as well as by studying their crystalline morphology. Afterwards, the copolymers have been processed into films to evaluate their applicability as dielectric materials, by studying their thermal stability and dielectric response., [ES] En este proyecto se ha llevado a cabo la síntesis de una serie de copolímeros de propileno con una olefina funcionalizada, portadora de un grupo pirrol. La funcionalización de olefinas es un campo actual de estudio que persigue conseguir materiales que, a la vez que mantienen sus propiedades aislantes, podrían utilizarse con ventaja en dispositivos de almacenamiento de energía, gracias a su mayor permitividad, a su mayor estabilidad térmica y mecánica o a ambas. La síntesis se ha llevado a cabo mediante catálisis metalocénica, en un intervalo de composiciones determinado. Los materiales obtenidos se han caracterizado a nivel molecular mediante el análisis de su microestructura en composición y en configuración, así como mediante el estudio de su morfología cristalina. Posteriormente, los copolímeros se han procesado en forma de filmes para evaluar su aplicabilidad como materiales dieléctricos, mediante el estudio de su estabilidad térmica y su respuesta dieléctrica.

The dielectric response measurement is an important technique to assess the properties of insulation materials. However, the widely used approach with contact between samples and electrodes can in some cases limit the accuracy of the measurement. In this paper, an easily fabricated design is introduced and used to perform non-contact measurements. Air-reference measurements, comparing the sample to an air-gap for improved calibration, are used for all measurements. Results obtained by contact and non-contact methods, and with the feedback of electrometer locked and unlocked are compared. The effect of the pressure applied by the electrode is also investigated for both non-contact and contact measurements. Results show that the non-contact method can be an alternative to reduce contact problems between the sample and electrodes. For air-reference measurements, the impedance measurement instrument should be forced to use the same reference component for the air and sample measurements. Results obtained by the non-contact measurements are less sensitive to the pressure compared to that by contact measurements., QC 20210621

Aging of high voltage generators and motors lead to changes in the dielectric properties of the stator winding insulation system. Research on the relation between aging and dielectric response has been going on for decades. A particular challenge is that the coil insulation consists of several materials: two that strongly affect the dielectric response are the ground-wall insulation and the stress grading shield (end-corona protection, ECP), which exhibit quite different properties. The influence of the ECP on the overall dielectric response of the insulation system might dwarf the condition change of the ground-wall insulation. In this paper, we introduce a test system that can measure the dielectric response in both time and frequency domain from low to rated voltage. Measurement results of two types of custom-designed, commercial standard stator winding coils are presented, and the influence of the ECP can be observed. The validity of time-frequency domain transformation of this nonlinear system is discussed. This paper acts as a basis for the application of dielectric diagnostic testing in the field., QC 20211005

The dielectric response measurement is an important technique to assess the properties of insulation materials. However, the widely used approach with contact between samples and electrodes can in some cases limit the accuracy of the measurement. In this paper, an easily fabricated design is introduced and used to perform non-contact measurements. Air-reference measurements, comparing the sample to an air-gap for improved calibration, are used for all measurements. Results obtained by contact and non-contact methods, and with the feedback of electrometer locked and unlocked are compared. The effect of the pressure applied by the electrode is also investigated for both non-contact and contact measurements. Results show that the non-contact method can be an alternative to reduce contact problems between the sample and electrodes. For air-reference measurements, the impedance measurement instrument should be forced to use the same reference component for the air and sample measurements. Results obtained by the non-contact measurements are less sensitive to the pressure compared to that by contact measurements., QC 20210621

Aging of high voltage generators and motors lead to changes in the dielectric properties of the stator winding insulation system. Research on the relation between aging and dielectric response has been going on for decades. A particular challenge is that the coil insulation consists of several materials: two that strongly affect the dielectric response are the ground-wall insulation and the stress grading shield (end-corona protection, ECP), which exhibit quite different properties. The influence of the ECP on the overall dielectric response of the insulation system might dwarf the condition change of the ground-wall insulation. In this paper, we introduce a test system that can measure the dielectric response in both time and frequency domain from low to rated voltage. Measurement results of two types of custom-designed, commercial standard stator winding coils are presented, and the influence of the ECP can be observed. The validity of time-frequency domain transformation of this nonlinear system is discussed. This paper acts as a basis for the application of dielectric diagnostic testing in the field., QC 20211005

Aging of high voltage generators and motors lead to changes in the dielectric properties of the stator winding insulation system. Research on the relation between aging and dielectric response has been going on for decades. A particular challenge is that the coil insulation consists of several materials: two that strongly affect the dielectric response are the ground-wall insulation and the stress grading shield (end-corona protection, ECP), which exhibit quite different properties. The influence of the ECP on the overall dielectric response of the insulation system might dwarf the condition change of the ground-wall insulation. In this paper, we introduce a test system that can measure the dielectric response in both time and frequency domain from low to rated voltage. Measurement results of two types of custom-designed, commercial standard stator winding coils are presented, and the influence of the ECP can be observed. The validity of time-frequency domain transformation of this nonlinear system is discussed. This paper acts as a basis for the application of dielectric diagnostic testing in the field., QC 20211005

The dielectric response measurement is an important technique to assess the properties of insulation materials. However, the widely used approach with contact between samples and electrodes can in some cases limit the accuracy of the measurement. In this paper, an easily fabricated design is introduced and used to perform non-contact measurements. Air-reference measurements, comparing the sample to an air-gap for improved calibration, are used for all measurements. Results obtained by contact and non-contact methods, and with the feedback of electrometer locked and unlocked are compared. The effect of the pressure applied by the electrode is also investigated for both non-contact and contact measurements. Results show that the non-contact method can be an alternative to reduce contact problems between the sample and electrodes. For air-reference measurements, the impedance measurement instrument should be forced to use the same reference component for the air and sample measurements. Results obtained by the non-contact measurements are less sensitive to the pressure compared to that by contact measurements., QC 20210621

Aging of high voltage generators and motors lead to changes in the dielectric properties of the stator winding insulation system. Research on the relation between aging and dielectric response has been going on for decades. A particular challenge is that the coil insulation consists of several materials: two that strongly affect the dielectric response are the ground-wall insulation and the stress grading shield (end-corona protection, ECP), which exhibit quite different properties. The influence of the ECP on the overall dielectric response of the insulation system might dwarf the condition change of the ground-wall insulation. In this paper, we introduce a test system that can measure the dielectric response in both time and frequency domain from low to rated voltage. Measurement results of two types of custom-designed, commercial standard stator winding coils are presented, and the influence of the ECP can be observed. The validity of time-frequency domain transformation of this nonlinear system is discussed. This paper acts as a basis for the application of dielectric diagnostic testing in the field., QC 20211005

The dielectric response measurement is an important technique to assess the properties of insulation materials. However, the widely used approach with contact between samples and electrodes can in some cases limit the accuracy of the measurement. In this paper, an easily fabricated design is introduced and used to perform non-contact measurements. Air-reference measurements, comparing the sample to an air-gap for improved calibration, are used for all measurements. Results obtained by contact and non-contact methods, and with the feedback of electrometer locked and unlocked are compared. The effect of the pressure applied by the electrode is also investigated for both non-contact and contact measurements. Results show that the non-contact method can be an alternative to reduce contact problems between the sample and electrodes. For air-reference measurements, the impedance measurement instrument should be forced to use the same reference component for the air and sample measurements. Results obtained by the non-contact measurements are less sensitive to the pressure compared to that by contact measurements., QC 20210621

ABINIT is probably the first electronic-structure package to have been released under an open-source license about 20 years ago. It implements density functional theory, density-functional perturbation theory (DFPT), many-body perturbation theory (GW approximation and Bethe–Salpeter equation), and more specific or advanced formalisms, such as dynamical mean-field theory (DMFT) and the “temperaturedependent effective potential” approach for anharmonic effects. Relying on planewaves for the representation of wavefunctions, density, and other space-dependent quantities, with pseudopotentials or projector-augmented waves (PAWs), it is well suited for the study of periodic materials, although nanostructures and molecules can be treated with the supercell technique. The present article starts with a brief description of the project, a summary of the theories upon which ABINIT relies, and a list of the associated capabilities. It then focuses on selected capabilities that might not be present in the majority of electronic structure packages either among planewave codes or, in general, treatment of strongly correlated materials using DMFT; materials under finite electric fields; properties at nuclei (electric field gradient, Mössbauer shifts, and orbital magnetization); positron annihilation; Raman intensities and electro-optic effect; and DFPT calculations of response to strain perturbation (elastic constants and piezoelectricity), spatial dispersion (flexoelectricity), electronic mobility, temperature dependence of the gap, and spin-magnetic-field perturbation. The ABINIT DFPT implementation is very general, including systems with van der Waals interaction or with noncollinear magnetism. Community projects are also described: generation of pseudopotential and PAW datasets, high-throughput calculations (databases of phonon band structure, second-harmonic generation, and GW computations of bandgaps), and the library LIBPAW. ABINIT has strong links with many other software p

In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz., QC 20201008

In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz., QC 20201008

In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz., QC 20201008

The purpose of this work was to synthesize and study magnetic properties of composite films consisting of Gd-Co ferrimagnetic system and Al2O3 dielectric matrix. GdCo-Al2O3 films of different composition were synthesized by magnetron co-sputtering of Gd, Co, and Al2O3 targets in an Ar atmosphere. Investigation of magnetic properties was carried out using a vibrating sample magnetometer in the temperature range from 10 to 300 K. The obtained results showed that in the composite system with a volume of dielectric material exceeding 50% a superparamagnetic state is realized, indicating granular microstructure. In this case, the granules show signs of ferrimagnetic ordering. © Published under licence by IOP Publishing Ltd.

Dielectric properties of polyvinylidene fluoride based thin films and electrospun mats have been studied. Frequency dependences of samples capacity and tangent of dielectric losses have been obtained. The influence of trifluoroethylene presence in copolymer on dielectric properties has been investigated. Efficiency of using deposited contacts instead of pressed contacts was considered. © Published under licence by IOP Publishing Ltd.

This work reports a phenomenological comparative study of atmospheric pressure barrier plasmas using ferroelectric (ferroelectric barrier discharge (FBD)) and dielectric (dielectric barrier discharge (DBD)) plates to moderate the discharge. For FBD operation and large inter-electrode distances, experiments with helium carried out in a parallel plate reactor as a function of applied voltage have shown an enhancement of one order of magnitude in the charge transferred through the circuit. In a similar way to DBDs, FBDs rendered a laterally localized arrangement of discrete columnar discharges with a pattern distribution and an overall current intensity that depended on operation conditions. However, unlike the regular columnar pattern found for DBD operation, discharge columns in the FBD mode appear randomly and inhomogeneously distributed on the ferroelectric surface. This geometrical behavior of FBD plasma columns, as well as the singular variation of current with applied voltage and the particular shape characteristics of the current discharge curves have been accounted for by the high capacity of ferroelectric surfaces to randomly accumulate charge and to promote the emission of secondary electrons in the presence of a plasma.

This work reports a phenomenological comparative study of atmospheric pressure barrier plasmas using ferroelectric (ferroelectric barrier discharge (FBD)) and dielectric (dielectric barrier discharge (DBD)) plates to moderate the discharge. For FBD operation and large inter-electrode distances, experiments with helium carried out in a parallel plate reactor as a function of applied voltage have shown an enhancement of one order of magnitude in the charge transferred through the circuit. In a similar way to DBDs, FBDs rendered a laterally localized arrangement of discrete columnar discharges with a pattern distribution and an overall current intensity that depended on operation conditions. However, unlike the regular columnar pattern found for DBD operation, discharge columns in the FBD mode appear randomly and inhomogeneously distributed on the ferroelectric surface. This geometrical behavior of FBD plasma columns, as well as the singular variation of current with applied voltage and the particular shape characteristics of the current discharge curves have been accounted for by the high capacity of ferroelectric surfaces to randomly accumulate charge and to promote the emission of secondary electrons in the presence of a plasma.

In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz., QC 20201008

In this study, nanocrystalline (18-28 nm) perovskite-like bismuth ferrite rare earth-doped powders (Bi0.9RE0.1FeO3, where RE = La (BLaFO), Eu (BEuFO), and Er (BErFO)) were obtained by microwave-assisted modification of solution combustion synthesis (SCS). The influence of high load La3+, Eu3+, and Er3+ doping on structural, optical, and electrical properties of BiFeO3 was investigated. It was found that rare earth doping along with fast phase formation and quenching significantly distorts the crystal cells of the obtained materials, which results in the formation of mixed rhombohedral- (R3c-) orthorhombic (Pbnm) crystal structures with decreased lengths of Bi-O and Fe-O bonds along with a decreasing radius size of doping ions. This promotes reduction of the optical band gap energy and suppression of ionic polarization at high frequencies and results in enhanced dielectric permittivity of the materials at 1 MHz., QC 20201008

A brief survey is presented on the methods aimed at rigorous validation of the occurrence of complex RCS resonances for canonical structures: dielectric and perfectly conducting cylinders covered by layered media possessing circular symmetry. It is shown that the resonances are associated with singularities of the scattered field in the complex domain. © 2019 IEEE.

[Abstract]: In the past decade, responsive photonic crystals (RPCs) have acquired considerable attention. Their unique responsiveness provides a wide range of applications in different fields. RPCs show advantages in anticounterfeiting and information encryption technologies but they are arising as a new trend in biomedicine: detection of different diseases, drug delivery and tumor screening. Among different types of RPCs, colloidal assembled magnetic responsive photonic crystals are the most interesting due to their reversible and tunable response to magnetic fields. The magnetic responsive photonic crystals prepared in this Master’s Final Project, are characterized by their magnetochromism: a reversible and tunable change in their color in response to the application of a magnetic field. Superparamagnetic Fe3O4 colloidal nanocrystal clusters (MCNCs) with a core-shell structure were synthesized. MCNCs were prepared using a modified one-pot solvothermal method where anionic polyelectrolyte poly(4styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) was used as stabilizer to obtain the core. A modified Stöber process was applied for silica coating to complete the nanostructure. The obtained nanoparticles were characterized by powder X-Ray Diffraction (XRD), Infrared Spectoscopy (IR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Dynamic Light Scattering (DLS), and Electrophoretic Light Scattering (ELS). Moreover, magnetization curve and magnetic hyperthermia measurements were performed. The results showed monodisperse magnetic nanoparticles with a superparamagnetic behavior and high heating power. Furthermore, the ordering of the nanoparticles into 3D chain-like structures was observed in the presence of a magnetic field and evenmore this peculiar arrangement can be modified by the applied magnetic field. A rheological study was designed and carried out, showing that the suspension presents a behavior, [Resumo]: Na década pasada os cristais fotónicos de resposta (RPCs) adquiriron unha considerable atención. A súa única capacidade de resposta proporciona un amplo rango de aplicacións en diferentes campos. Os RPCs mostran vantaxes na prevención das falsificacións e nas tecnoloxías de encriptación de información, mais preséntanse coma unha nova tendencia na biomedicina: detección de diferentes enfermidades, administración de fármacos e revisión de tumores. Entre os diferentes tipos de RPCs, os cristais fotónicos de resposta magnética con ensamblado coloidal son os máis interesantes debido á súa resposta reversible e regulable aos campos magnéticos. Os cristais fotónicos de resposta magnética preparados neste Traballo de Fin de Mestrado caracterízanse polo seu magnetocromismo: un cambio reversible e regulable na súa cor en resposta á aplicación dun campo magnético. Sintetizáronse clusters coloidais superparamagnéticos de nanocristais de magnetita (MCNCs) cunha estrutura de tipo “core-shell”. Preparáronse empregando un proceso solvotermal “one-pot” modificado onde o polielectrolito aniónico empregado foi a sal de sodio do ácido poli(4-estirensulfónico-co-maleico) (PSSMA) como estabilizador para ober o núcleo. Un proceso de Stöber modificado aplicouse para obter o recubrimento de sílice que completa a nanoestrutura. S nanopartículas obtidas caracterizáronse mediante Difracción de Raios X (XRD) de po, Espectroscopía Infravermella (IR), Microscopía Electrónica de Transmisión (TEM), Microscopía Electrónica de Varrido (SEM), Análise Termogravimétrica (TGA), Dispersión de Luz Dinámica (DLS) e Dispersión de Luz Electroforética (ELS). Ademais realizáronse medidas da curva de magnetización e de hipertermia magnética. Os resultados mostran nanopartículas magnéticas cun comportamento superparamagnético e un alto poder de quecemento. Ademais, observouse o ordenamento das partículas en estruturas 3D en forma de cadeas en presenza dun campo magnético e amais esta peculiar disposició

The present research is devoted to the cationic-deficient SrMoO4‑based sheelite-related complex oxides. The doping with bismuth to A sublattice and codoping with bismuth and vanadium (to A and B sublattices, respectively) were discussed. The X-Ray powder diffraction and infrared spectroscopy were used to investigate structural characteristics of the complex oxides. In Sr1–1.5xBixMoO4, a superstructural ordering was observed. Conductivity and dielectric loss of ceramic samples are measured using alternating current.

The design of a microwave oscillator based on a microstrip log-periodic antenna integrated with a field effect transistor and a waveguide built in a dielectric substrate has been developed and analyzed. The waveguide geometry provides the possibility of propagation and radiation at both the fundamental frequency of the log-periodic antenna and harmonics. Computer simulation of the oscillator design in a frequency range near resonance frequencies of the log-periodic antenna is conducted. The possibility of summation of powers of several antenna–oscillators arranged ias a linear phased array is investigated., QC 20181023