Letteratura scientifica selezionata sul tema "Antennas"
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Articoli di riviste sul tema "Antennas"
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Ghodake, Asha, e Balaji Hogade. "ISM Band 2.4 GHz Wearable Textile Antenna for Glucose Level Monitoring". International Journal of Electrical and Electronics Research 11, n. 1 (30 marzo 2023): 39–43. http://dx.doi.org/10.37391/ijeer.110106.
Testo completoAbstract (sommario):
Wearable technology has recently attracted much interest for various uses. An essential component of the wearable system is the wearable antenna. Textile and non-textile materials have both been used to create wearable antennas. Textile antennas are very useful and widely used nowadays, particularly in body-worn applications monitoring health parameters. Fabricated using microstrip technology, textile antennas have various benefits, including small size, lightweight, simple fabrication, and ease of wear. In this study, a microstrip antenna is created utilizing a substrate made of jeans. It works between 2.4 to 2.5 GHz in the ISM (industrial, scientific, and medical) band. High-frequency structure simulator (HFSS) software was used to simulate two antennas, one with an incomplete and the other with a complete ground plane. Wearable antennas can protect the body from the impacts of RF radiation by utilizing the entire ground plane principle. Results from a vector network analyzer were obtained for the fabricated antenna (VNA). This antenna's main function is to track blood glucose levels. Blood's dielectric characteristics change when blood sugar levels fluctuate, affecting the antenna’s output frequency. There are two ways to monitor glucose levels. One method requires placing a finger on an antenna patch, while the other involves fixing an antenna to a person's arm and detecting the output frequency fluctuation. The antenna's resonant frequency raises in reaction to increased blood glucose levels. Therefore, these textile antennas are a great choice for non-blood sample monitoring of blood glucose levels.
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Fu, Xiaoyi, Yuntao Hua, Wenlai Ma, Hutao Cui e Yang Zhao. "Thermal field simulation and material parameter optimization for spaceborne annular truss antennas". Journal of Physics: Conference Series 2691, n. 1 (1 gennaio 2024): 012054. http://dx.doi.org/10.1088/1742-6596/2691/1/012054.
Testo completoAbstract (sommario):
Abstract The operational efficacy of large spaceborne annular truss antennas in orbit is significantly influenced by solar irradiation and alternating Earth shadow. This antenna system periodically encounters diverse extreme environments that impact the precision of the antenna surface performance. Consequently, this study presents an optimized thermal control design and conducts temperature field simulation calculations for such antennas. Initial efforts are directed toward analyzing the variables influencing the antenna structure’s temperature, with specific attention paid to the distinctive compositional characteristics of high-precision antennas. As a subsequent step, orthogonal tests are implemented, facilitating the development of an antenna thermal analysis model. This model assists in the identification of principal variables influencing the antenna’s temperature field. Finally, the antenna’s optimal thermal design is drawn upon the biogeography-based optimization (BBO) algorithm, enabling the derivation of ideal material parameters for the thermal design of the antenna. This methodology offers theoretical guidance for future thermal control design of large spaceborne annular truss antennas.
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Saeidi, Tale, Idris Ismail, Wong Peng Wen, Adam R. H. Alhawari e Ahmad Mohammadi. "Ultra-Wideband Antennas for Wireless Communication Applications". International Journal of Antennas and Propagation 2019 (22 aprile 2019): 1–25. http://dx.doi.org/10.1155/2019/7918765.
Testo completoAbstract (sommario):
A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented. These antennas which are taken into account are listed as wide-band microstrip antenna, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, metamaterial (MTM) structure UWB antennas, elliptical printed monopole UWB antenna, and flexible wearable UWB antenna. The antennas’ performance is compared based on their size and how they can be applicable for portable communication device applications. This review paper furnishes a proper direction to select varieties of figures in terms of impedance bandwidth, gain, directivity, dimensions, time domain characteristics, and materials affecting these antenna’s characteristics.
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Yeom, Insu, Junghan Choi, Sung-su Kwoun, Byungje Lee e Changwon Jung. "Analysis of RF Front-End Performance of Reconfigurable Antennas with RF Switches in the Far Field". International Journal of Antennas and Propagation 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/385730.
Testo completoAbstract (sommario):
The RF front-end performances in the far-field condition of reconfigurable antennas employing two commonly used RF switching devices (PIN diodes and RF-MEMS switches) were compared. Two types of antennas (monopole and slot) representing general direct/coupled feed types were used for the reconfigurable antennas to compare the excited RF power to the RF switches by the reconfigurable antenna types. For the switching operation of the antennas, a biasing circuit was designed and embedded in the same antenna board, which included a battery to emphasize the antenna’s adaptability to mobile devices. The measurement results of each reconfigurable antenna (radiation patterns and return losses) are presented in this study. The receiving power of the reference antenna was measured by varying the transmitting power of the reconfigurable antennas in the far-field condition. The receiving power was analyzed using the “Friis transmission equation” and compared for two switching elements. Based on the results of these measurements and comparisons, we discuss what constitutes an appropriate switch device and antenna type for reconfigurable antennas of mobile devices in the far-field condition.
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Gargi, C., J. S. Kennedy e T. D. Jayabal. "Morphometrics and distribution of antennal sensillae of both sexes of Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)". Journal of Applied and Natural Science 14, SI (15 luglio 2022): 41–48. http://dx.doi.org/10.31018/jans.v14isi.3563.
Testo completoAbstract (sommario):
Fall Armyworm, Spodoptera frugiperda, is a devastating invasive pest persisting as a menace hampering the progress of Indian agriculture. The morphometrics and distribution of antennal sensilla of both sexes of S. frugiperda were investigated in the study. The antenna was filiform for both sexes and was composed of scape, pedicel and flagellum. Male antennas had more subsegments (65-71) in the flagellum than female (56-70) antennas. Male and female S. frugiperda antennae possessed eight types of sensilla: sensilla trichoidea, sensilla chaetica, sensilla coeloconica, sensilla styloconica, sensilla basiconica, sensilla auricillica, sensilla squamiformia and Bӧhm’s bristles. Sensilla trichoidea was the most abundant sensilla found in the antenna of both sexes and was more abundant in males than in females. It was also noticed that male antenna was longer than the female antenna. The results of the present study helps to assess alternative management strategies with an electrophysiological response of the pest towards sex pheromones and in combination with plant info chemicals for monitoring and management of S. frugiperda in agricultural ecosystems.
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Ramalakshmi, Gudla, e P. Mallikarjuna Rao. "A Novel Metamaterial Inspired 2nd Iteration Koch Fractal Antenna for Wi-Fi, WLAN, C band and X band Wireless Communications". Journal of Physics: Conference Series 2062, n. 1 (1 novembre 2021): 012004. http://dx.doi.org/10.1088/1742-6596/2062/1/012004.
Testo completoAbstract (sommario):
Abstract The rapid advancements in wireless technology desires compact, miniaturized, multiband and ultra wideband antennas. Fractal antennas have been proved as a source for fulfilling these demands. In this paper a 2nd order Koch fractal antenna of size 29.6 × 35.7mm2 designed on FR4-epoxy substrate material of dielectric constant (ɛr) 4.4 with a height of 1.6mm. This antenna is named as ANTENNA-1. To increase this antenna’s performance a meta material unit cell has been placed on the ground plane to serve multi band applications and is named as ANTENNA-2, which is the proposed antenna in this paper. The simulations have been carried out for both the antennas using ANSYS HFSS tool over the frequency sweep of (1-12GHz). The simulation results of proposed antenna producing 7 frequency bands which serves Wi-Fi, WLAN, C-band, and X band wireless communications. The simulation results like return loss, VSWR values have a good matching with the measured return loss, VSWR results of the fabricated antenna
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Sedghi, Tohid, Mahdi Jalali e Tohid Aribi. "Fabrication of CPW-Fed Fractal Antenna for UWB Applications with Omni-Directional Patterns". Scientific World Journal 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/391602.
Testo completoAbstract (sommario):
Novel and compact CPW-fed antennas are proposed comprised of a fractal patch and modified ground-plane. The ground-plane is truncated at the center and includes dielectric notches at its side to enhance the antenna’s impedance bandwidth. The dimensions of the notches effectively control the upper and lower band edges of the antenna. The optimized antenna operates across 2.95–12.81 GHz forS11≤-10 dB. Omnidirectional radiation pattern is achieved over the full UWB frequency range. The miniaturized antenna has a total size of14×18×1 mm3. The characteristics of the proposed antenna are suitable for UWB wireless communication requiring low profile antennas.
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Korkmaz, Sumeyye, Mohammad Alibakhshikenari e Lida Kouhalvandi. "A Framework for Optimizing Antenna Through Genetic Algorithm-Based Neural Network". Acta Marisiensis. Seria Technologica 20, n. 1 (1 giugno 2023): 49–53. http://dx.doi.org/10.2478/amset-2023-0009.
Testo completoAbstract (sommario):
Abstract In this research paper, the application of Artificial Neural Networks (ANN) for designing antennas is introduced. The primary objective of this optimization technique is to focus on the antenna’s parameters to achieve a desirable S11 value, which is a key metric of an antenna’s performance. To demonstrate the effectiveness of this approach, the optimization method to design three different antennas using the Numerical Analyzer (MATLAB) tool is employed. Through this study, it is tried to provide new insights into the optimization of antenna design using ANN and demonstrate its potential applications in the field of antenna engineering. The results of this research could potentially lead to the development of more efficient and effective antenna systems with improved performance in various applications.
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Mohan, Anand, e M. Sundararajan. "FRACTAL ANTENNA – WIRELESS COMMUNICATION NEW BEGINNING BREAKTHROUGH IN DIGITAL ERA". Acta Informatica Malaysia 4, n. 1 (23 gennaio 2020): 01–06. http://dx.doi.org/10.26480/aim.01.2020.01.06.
Testo completoAbstract (sommario):
In this digital era, we are subject to cellular gadgets, there has been an expanding demand in antennas that are smaller, conformal, and broadband. Fractal antenna wire utilizes a self-comparative structure to expand the length of a material in an all-out surface zone. Fractal Antenna Systems creates and constructs the smaller, most astounding execution Wideband/multiband antennas on the planet. These antennas are regularly two to multiple times smaller than conventional aerials, while accomplishing remarkable recurrence inclusion and magnificent gains and power designs. Fractal Antenna’s items have been demonstrated in the toughest business, military, and government applications. Fractal antennas apparatuses depend on mind boggling rehashing geometrical shape shaving novel traits that make them particularly significant for broadcast communications and different remote needs. Their requirements are not well met by Traditional antennas apparatuses. Applications for fractal geometries in cell gadgets have turned out to be hotly debated issues of research in science and building due to buyer request.
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R, Murugasamy, Abirami P, Aruna P, Dharani S e Divyasri M. "IoT Based Antenna Positioning System". International Journal for Research in Applied Science and Engineering Technology 11, n. 3 (31 marzo 2023): 1689–95. http://dx.doi.org/10.22214/ijraset.2023.49758.
Testo completoAbstract (sommario):
Abstract: Proper positioning of antennas is necessary for wireless communication. So herewe are giving a project on an IOT based antenna positioning system that allows for remotely positioning of antennas based over IOT. The method that is used here to control the antennas position is by using Arduino UNO R3 and Servo motors. The Blynk app acts as a remote and is used to send the signal to the Arduino through the internet. The project helps to control the antenna’s positionby the user’s command. If we have android mobile with internet connection, we can easily access the antenna position. Also to monitor the environmental conditions we have used temperature, humidity and raindrop sensors.
Tesi sul tema "Antennas"
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Rouibah, Ammar. "Un modèle analytique pour l'antenne microruban rectangulaire". Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209359.
Testo completoAbstract (sommario):
Les antennes microruban et en particulier l’antenne microruban rectangulaire sont étudiées et utilisées depuis plusieurs dizaines d’années.Comme pour toute antenne, il est important de disposer pour ces antennes d’un modèle analytique qui permette une bonne compréhension du fonctionnement et fournisse de manière rapide des valeurs pour les principaux paramètres (fréquence de travail, impédance, gain, rendement et bande passante).
Au fil des ans, deux modèles, chacun comprenant de nombreuses variantes, ont été développés :le modèle dit « de la ligne de transmission » et le modèle dit « de la cavité ». Ces modèles sont soit peu rigoureux, soit complexes et donnent souvent des résultats assez éloignés de la réalité.
L’objectif de ce travail est double :définir un modèle qui soit d’une part aussi simple et direct que possible et d’autre part aussi précis que possible.
Le premier objectif est atteint dans la mesure où on n’utilise que la loi fondamentale du rayonnement des courants réels (électriques) en excluant tout recours à des courants virtuels (magnétiques).
Concernant l’objectif de précision, des comparaisons nombreuses avec des résultats d’un simulateur purement numérique et des mesures indiquent une amélioration pour tous les paramètres mais en particulier pour l’impédance qui est le point faible de tous les modèles existants.
Microstrip antennas and the rectangular microstrip antenna in particular have been studied and used for several decades.
As every antenna, the microstrip antenna requires a good analytical model that provides physical insight and an easy prediction of the antenna parameters (resonance frequency, impedance, gain, efficiency and bandwidth).
Over the years, two families of models have been developed, each involving many variants: the “transmission line” and the “cavity” models. These models either lack accuracy or are very complex and produce results that may be far away from reality.
The objective of this work is double: defining a model as simple and direct as possible and on the other hand as accurate as possible.
The first objective has been reached as all our calculations rest on the fundamental radiation formula by real (electrical) currents excluding any virtual (magnetic) currents.
Regarding accuracy, comparisons to numerical simulations and measurements show an improvement, in particular with regard to the prediction of the impedance parameters, which is the weak point of all existing models.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Sonkki, M. (Marko). "Wideband and multi-element antennas for mobile applications". Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201085.
Testo completoAbstract (sommario):
Abstract This dissertation presents wideband and multi-element antennas for mobile applications. It is divided into the following main parts: modal theory, wideband antennas, multi-element antennas, and wideband multi-element antennas. The radiating fields are first studied in terms of spherical scalar and vector modes, and it is shown how these modes correlate with the characteristic current modes on a planar mobile ground plane. The theory part shows how it is possible to excite the same modes on a conventional sphere and a rectangular planar mobile ground plane. The theory refers to the novel wideband antenna structures presented in this dissertation, in terms of current and radiating modes. After studying the modes, the dissertation shows how to excite a radiating antenna mode within a wide frequency bandwidth. To gain this, two main approaches are taken. First, a quasi-complementary antenna (QCA) structure with an electric conductor and magnetic slot is presented, and its characteristics are studied. A QCA UWB antenna, and a QCA element excited with a monopole or a dipole, is presented. The QCA structure compensates for the imaginary part of the input impedance on wide frequency bandwidth, when, at the same time, the fundamental mode is excited to ensure good radiating properties. The second approach uses a symmetrical feeding with two antenna elements to gain a wide frequency bandwidth, the relative -6 dB impedance bandwidth between 37.5–80%. When a field is symmetrically coupled to the conducting ground plane, the excitation avoids the awakening of higher order modes which might disturb the performance of the antenna. It is also shown, by using multiple feeding elements, that the excitation of orthogonal higher order modes on a small radiating ground plane is possible. As the modes are orthogonal to each other, they present a very low correlation. By using this kind of approach, radiation pattern diversity can be obtained in mobile applications within a small volume. On the other hand, when combining two QCA elements to a one multi-element antenna structure, a wideband diversity antenna with an 87.5% relative -6 dB impedance bandwidth, and a wideband MIMO antenna with a 95.0% relative -6 dB impedance bandwidth, are presented with excellent radiation and correlation properties. Also mutual coupling is need to be counted when multi-element antennas are designed. When designing an efficient radiator, it is important to consider an antenna feeding in terms of wideband impedance matching and wideband baluns, not to spoil the antenna performance. The efficient antenna structures and feeding mechanisms are obtained by using commercial 3D electromagnetic simulators to find the desired wideband antenna characteristics. Prototype antennas are measured in most of the presented structures to show their functionality in real. In general, the dissertation presents wideband antenna structures with radiating antenna modes excited on a planar conducting ground plane. The idea is to find structures and feeding mechanisms to excite the fundamental mode, or a certain radiating antenna mode, at a wide frequency bandwidth, by avoiding the excitation of higher order modes which might disturb the antenna performance. It is also shown that, by using multiple feeding elements, it is possible to excite higher order modes on a small antennaTiivistelmä Väitöskirjassa esitetään uusia laajakaistaisia ja monielementtiantenneja matkaviestimiin. Väitöskirja koostuu neljästä pääalueesta: pintavirtojen muototeoria, laajakaistaiset antennit, monielementtiantennit sekä laajakaistaiset monielementtiantennit. Teoriaosassa säteilykenttiä on aluksi tutkittu pallon pinnalla sekä skalaaripotentiaaleina että pintavirtavektoreina, jonka jälkeen niitä on verrattu mobiilin laitteen maatason ominaispintavirtojen synnyttämiin säteilykenttiin. Teoriaosassa osoitetaan, että pallon pinnalla sekä tasomaisella suorakaiteen muotoisella pinnalla on mahdollista herättää samat säteilykentät. Myöhemmin väitöskirjassa esitettävien uudenlaisten antennirakenteiden ominaisuuksia verrataan teoriaosassa esitettyihin pintavirtoihin ja säteilykenttiin. Teoriaosuuden jälkeen osoitetaan miten säteilevä sähkömagneettinen kenttä saadaan herätettyä laajalla taajuusalueella. Tähän on otettu kaksi eri lähestymistapaa, joista ensimmäisessä esitellään ja tutkitaan kvasikomplementaarista antennirakennetta (QCA). Kvasikomplementaarisessa antennirakenteessa sisääntuloimpedanssin imaginaariosa kompensoidaan yhdistämällä sähköinen johde ja magneettinen rako samaan antenniin. Samanaikaisesti perusmuoto herätetään laajalla taajuusalueella, jolla varmistetaan antennin hyvät säteilyominaisuudet koko toimintataajuusalueella. Toisessa lähestymistavassa käytetään kahta symmetrisesti asetettua antennielementtiä, joita syötetään symmetrisesti samalla amplitudilla ja vaiheella. Kun sähkömagneettinen kenttä herätetään symmetrisesti, korkeamman kertaluvun muotojen herättäminen voidaan välttää laajalla taajuusalueella. Symmetrisesti syötetyillä antennirakenteilla saavutettu -6 dB suhteellinen impedanssikaistanleveys on 37.5–80 %. Useita syöttöelementtejä käytettäessä voidaan mobiilin laitteen maatasossa herättää yhdellä pistetaajuudella monta toisistaan riippumatonta säteilykenttää. Koska herätetyt kentät ovat toisistaan riippumattomia, on niiden välinen korrelaatio myös pieni. Kyseisellä rakenteella on mahdollista toteuttaa säteilykuviodiversiteetti erittäin pienessä tilassa, kuten matkapuhelimessa. Toisaalta, kun yhdistetään kaksi QCA-elementtiä yhdeksi monielementtiratkaisuksi, voidaan toteuttaa laajakaistainen diversiteettiantenni, jonka suhteellinen -6 dB impedanssikaistanleveys on 87.5 %. Vastaavasti kahdella laajakaistaisella QCA-elementillä toteutetulla MIMO-ratkaisulla päästään 95 % suhteelliseen -6 dB impedanssikaistanleveyteen. Molemmilla ratkaisuilla on erittäin hyvät säteilyominaisuudet sekä alhainen korrelaatio ja pieni keskinäiskytkentä antennielementtien välillä. Suunniteltaessa toimivaa laajakaistaista antennirakennetta, on tärkeää ottaa huomioon antennisyötön impedanssisovitus, jotta antennin suorituskyky ei heikkenisi. Lisäksi balansoidussa rakenteissa tulee olla laajakaistainen baluni, jolla vältetään säteilykuvion vääristyminen. Väitöskirjan syöttöratkaisuissa on käytetty kaupallisia sähkömagneettisia simulaattoreita, joilla antennirakenne voidaan mallintaa kolmiulotteisesti, ja joilla laajakaistainen syöttö saadaan optimoitua haluttuun antenniin. Suurin osa esitellyistä antennirakenteista on simulointien lisäksi myös mitattu, jolloin niiden toimivuus käytännössä pystytään todentamaan rakentamalla prototyyppiantenni. Yleisesti väitöskirjassa esitellään tasomaisia antenniratkaisuja johtavassa maatasossa, joissa säteilevät pintavirrat herätetään mahdollisimman laajalla taajuusalueella. Ideana on löytää laajakaistaisia antenni- ja syöttörakenteita, joilla saadaan herätettyä perusmuoto tai jokin muu haluttu muoto. Ajatuksena on välttää korkeamman kertaluvun muotojen herättäminen, jotka voivat pilata antennin suorituskyvyn. Väitöskirjassa osoitetaan myös, että pienikokoisella antennilla on mahdollista herättää korkeamman kertaluvun muotoja pistetaajuudella käyttämällä useita heräte-elementtejä
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Nikolayev, Denys. "Miniature antennas for biomedical applications". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S149.
Testo completoAbstract (sommario):
La télémétrie biomédicale et l’interfaçage neuronal à base de dispositifs miniatures et autonomes sans fil constituent de nouvelles applications en émergence. Elles visent à répondre à de nombreux enjeux y compris dans les domaines de la santé, du sport et bien être, ou encore de la sécurité au travail et de la défense. Parmi les applications typiques de biotélémétrie, nous pouvons citer le monitoring de certains paramètres physiologiques : température corporelle, pression artérielle, rythme cardiaque, taux de glucose et d’anticorps, détection d’agents chimiques, etc. En ce qui concerne l’interfaçage neuronal, il permet de restaurer les informations sensorielles, d’aider à la réadaptation des amputés, des personnes atteintes de paralysie ou des patients atteints de maladies neurodégénératives. L’objectif principal de cette thèse est de contribuer au développement de dispositifs miniaturisés et communicants pour le monitoring, en continu, de variables physiologiques d’humains ainsi que d’animaux. Ces dispositifs innovants nécessitent un système de communication fiable. Plus particulièrement, il s’agit d’analyser le milieu de propagation à l’intérieur des tissus biologiques et de développer des antennes miniatures innovantes ainsi que des méthodes pour leur analyse et leur caractérisation. Le verrou majeur concerne le rendement des antennes miniatures. Les effets de forte hétérogénéité, dispersion, pertes très élevées des milieux biologiques et les contraintes de miniaturisation et d’intégration dans des dispositifs in-body limitent la portée des systèmes existants à quelques dizaines de centimètres. Tout d’abord, des outils spécifiques de modélisation et d’optimisation ont été développés en collaboration avec l’Université de Bohème de l’Ouest. Ces outils sont indispensables pour l’analyse des composants de systèmes antennaires complexes : le code Agros2D (CAO interne) utilise des méthodes entièrement adaptatives. Cette approche permet de réduire la complexité d’optimisation des antennes in-body jusqu’un seul dégrée de liberté. Puis, la limite fondamentale de rendement des antennes pour les applications in-body a été définie ; les liens entre cette limite et la taille de l’antenne, sa fréquence de fonctionnement, la polarisation et les matériaux utilisés (dont hypothétiques) ont été quantifiés pour la première fois. Ce travail fondamental a d’abord pour objectif l’optimisation des performances de l’antenne actuelle de la capsule e-Celsius de l’entreprise BodyCAP pour accroître la portée de la gélule, en prenant en compte les caractéristiques des matériaux et le milieu de propagation que constituent les tissus biologiques. Dans cette étape on inclut également la fabrication des prototypes de gélules télémétriques ainsi que leurs mesures d’impédance. L’antenne optimisée a une portée trois fois plus importante que celle actuelle tout en occupant le même volume. En utilisant ces principes de conception, nous avons développé et caractérisé une antenne à 434 MHz adaptée à une large gamme d'applications in-body. Des dimensions ultra-miniatures, une robustesse et un rendement accrus permettent de l'utiliser à la fois pour des applications des capsules à implanter et à avaler. Enfin, en développant davantage les méthodes de conception et d’optimisation, nous avons conçu une antenne double-bande. Ayant la même robustesse que son équivalent actuel mono-bande, elle présente également un rendement encore plus élevé, permettant ainsi de fonctionner au-delà de 10 m. La caractéristique double-bande permet de concevoir les dispositifs in-body rechargeables sans fil dans le corps. Les antennes proposées contribuent au développement ultérieur d'une nouvelle génération de dispositifs miniatures in-body qui impliquent une intégration complexe et dense des capteurs, de la logique et de la source d'alimentationEmerging wireless biotelemetry using miniature implantable, ingestible or injectable (in-body) devices allows continuously monitor and yield human or animal physiological parameters while maintaining mobility and quality of life. Recent advances in microelectromechanical systems and microfluidics—along with ongoing miniaturization of electronics—have empowered numerous innovations in biotelemetry devices, creating new applications in medicine, clinical research, wellness, and defense. Among the typical applications, I can mention, for example, the monitoring of physiological variables: body temperature, blood pressure, heart rate, detection of antibodies, chemical, or biological agents. Biotelemetry devices require a reliable communication system: robust, efficient, and versatile. Improving the transmission range of miniature in-body devices remains a major challenge: for the time being, they are able to operate only up to a few meters. Among the main issues to face are low radiation efficiencies (< 0.1%), antenna impedance detuning, and strong coupling to lossy and dispersive biological tissues. Thus, the main goal of the thesis is to conduct a multi-disciplinary study on development, optimization and characterization of antennas for in-body biotelemetry devices. After state-of-the-art and the context, I start with the development on both physical and numerical approaches to account for the effect of human tissues on the antenna. I propose the methodology to achieve given electromagnetic properties at a given frequency based on the full factorial experiment and surface response optimization. In addition, I describe the spherical physical phantom for the far-field characterization along with a combination of feed decoupling techniques. I proceed by reviewing the trough-body propagation mechanisms and deriving the optimal frequency for the in-body devices. I formulate the problem using four phantoms (homogeneous and heterogeneous) and perform full-wave analysis using an in-house hp-FEM code Agros 2D. Next, I study the existing antenna used by the BodyCap Company for its e-Celsius capsule and the ways on how to improve its operating range and robustness under strict integration and material constraints. The mechanisms of antenna–body coupling are analyzed and the found solution improves the antenna IEEE gain by 11 dBi (the operating range is at least tripled). The existing matching circuit and balun are optimized too for the given application reducing its size from eleven to seven discrete elements. In the following chapters, I continue studying the decoupling of antennas from a body using specific microstrip designs and dielectric loading via capsule shell. By applying the developed approaches, a high robustness and radiation efficiency can be achieved. At first, I develop a proof-of-concept antenna that demonstrates that the perfect matching (detuning immunity) is achievable for the operation within all human tissues. Based on these results, I develop a miniature and versatile biotelemetry platform: a 17 mm x 7 mm alumina capsule containing a conformal 434 MHz antenna. The antenna is well matched to 50 Ohm within the majority of human tissues and operates with an arbitrary device circuitry. Like this, one can use it ''as is,'' applying it for a wide range of in-body applications. Then, I develop a low profile conformal dual-band antenna operating in 434 MHz and 2.45 GHz bands. Such antenna can integrate both data transmission and wireless powering functionality increasing the available space inside an in-body device and increasing its scope of applications. Finally, I present the perspective developments including in-body sensing methodology. The obtained results contributes to further development of a new generation of miniature in-body devices that involve complex and dense integration of sensors, logic, and power sources
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Trinh, Le-Huy. "Antennes reconfigurables pour les applications mobiles et réseaux sans fil". Thesis, Nice, 2015. http://www.theses.fr/2015NICE4047/document.
Testo completoAbstract (sommario):
Au cours de ces dernières années, les technologies de télécommunication ont fait d'énormes progrès, notamment dans les communications mobiles et les réseaux de capteurs sans fil (WSN). Pour répondre à l’augmentation de la capacité de transmission et à l’amélioration de la qualité des canaux de communications mobiles, l’élargissement de la bande de fonctionnement est nécessaire par l'utilisation d'antennes reconfigurables en fréquence. En outre, dans les applications WSN, afin de réduire les collisions, d’augmenter la distance de communication et d'optimiser la consommation, l’utilisation d’antennes reconfigurables en directivité est une bonne solution. Dans ce cadre, nos travaux de recherche ont portés sur la conception de différentes structures antennaires reconfigurables. Dans un premier temps nous avons réalisés une antenne reconfigurable à base de nouveaux éléments actifs, les digitally tunable capacitors (DTC). Ces composants sont de très bons candidats en vue d’une intégration d'antennes pour des applications communications mobiles et WSN. Ensuite nous nous sommes attachés à concevoir des structures multibande, MIMO et reconfigurables en fréquence, permettant d’augmenter la bande de fréquence de fonctionnement du système de communication, d'optimiser l'efficacité et la qualité spectrale et d'améliorer la qualité de canal. Enfin, une autre voie a été explorée, l’utilisation d’antennes reconfigurables en directivité pour des applications de WSN. Les résultats de simulation et de mesure sont également présentés dans ce chapitre. Grâce à l'utilisation de ce type de structures, la performance des WSN a été optimiséeIn recent years, telecommunication technologies have enormous progress, especially cellular communications and wireless sensor networks. To meet the demand of increasing transmission capacity, improving quality of cellular communication channels, expanding the operating band of the equipment is necessary. As passive antenna has reached the limit on increasing the operating band with the small size, the use of frequency reconfigurable antenna is a feasible solution. Besides, in the applications of WSN, to reduce collisions, increase communication distance and optimize consumption, directional reconfigurable antenna is a good proposal. In this thesis we present several reconfigurable antenna structures. Firstly, a new component is introduced; digitally tunable capacitor (DTC). Thanks to its advantages, such parts are good candidate to be integrated in the antenna for cellular communication and wireless sensor network applications. After, several antennas are introduced include multiband antenna, MIMO and frequency reconfigurable antenna, which can be used to extend the operating frequency band of the communication system, optimize spectral efficiency and quality improve channel quality. The structures of these antennas are introduced together with the results of simulation and measurement for the purpose of solving the challenges given in the future cellular communications systems. And then, the proposed approach to the design of reconfigurable directional antennas is presented. Several reconfigurable directional antennas, which are used in applications of WSN, are introduced. Thanks to the use of directional antennas reconfigurable, performance of WSN system will be optimized
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Kabalan, Aladdin. "Miniaturisation et modélisation d’antennes monopoles larges bandes utilisant des matériaux magnéto-diélectriques en bande VHF". Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S041/document.
Testo completoAbstract (sommario):
Les avions comportent plusieurs systèmes de navigation et de communication nécessitent des antennes VHF large bande. Réduire la taille de ses antennes est un enjeu majeur tout en gardant des bonnes performances. Cette thèse propose des nouvelles configurations d'antennes à profil bas utilisant des nouveaux matériaux nanocomposites non conducteurs constitués de nanoparticules magnétiques développés au Lab-STICC. Un monopole planaire large bande a été développé et optimisé avec un taux de miniaturisation de 60% grâce à l'utilisation d'un matériau magnéto-diélectrique de forte perméabilité et faible pertes couvrant seulement 5% de sa surface. Les résultats expérimentaux, en presque parfait accord avec les simulations, montrent que le diagramme de rayonnement est omnidirectionnel et que la polarisation est verticale, avec un bon niveau du gain. L'antenne monopole planaire insérée dans un MMD des dimensions limitées avec des pertes a été modélisée par un nouveau circuit équivalent multi résonant. Ce circuit est développé à partir de l'impédance d'entrée de l'antenne et des caractéristiques du MMD, et validé par les simulations avec un parfait accord entre les résultatsAirplanes with multiple navigation and communication systems require broadband VHF antennas. Reduce the size of these antennas is a major challenge while keeping good performances. This thesis proposes new configurations of low profile antennas using new nanocomposite non-conductive materials consisting of magnetic nanoparticles developed at Lab-STICC. A broadband planar monopole has been developed and optimized with a 60% miniaturization rate thanks to the use of a high permeability and low loss magneto-dielectric material covering only 5% of its surface. The experimental results, in almost perfect agreement with the simulations, show that the radiation pattern is omnidirectional and that the polarization is vertical, with a good level of gain. The planar monopole antenna inserted in a MMD of limited dimensions with losses was modeled by a new multi-resonant equivalent circuit. This circuit is developed from the input impedance of the antenna and the characteristics of the MMD. and validated by the simulations with a perfect agreement between the results
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Shahpari, Morteza. "Fundamental Limitations of Small Antennas". Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365747.
Testo completoAbstract (sommario):
The physical size and material properties of antennas are major limiting factors of the antennas performance. These limitations are usually manifested through parameters such as bandwidth, quality factor and efficiency. The presented research examines these fundamental limitations with specific focus on electrically small antennas, and a new bound for antenna efficiency is developed.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Gorla, Hemachandra Reddy reddy. "MINIATUIRIZED ULTRA-WIDEBAND ANTENNAS FOR WIRELESS COMMUNICATIONS". OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1905.
Testo completoAbstract (sommario):
Wireless communication is part of our daily life in several applications, such as cell phones, wireless printers, sensors, etc. Each wireless device requires at least one antenna to communicate with other devices. In 2002, Federal Communications Commission (FCC) assigned a frequency spectrum from 3.1 GHz to 10.6 GHz for ultra-wideband communications. Several narrowband antennas require to cover the entire range. Unlike narrowband antennas, ultra-wideband antennas need to cover the wide frequency band. This research mainly focuses on physically small antenna designs. The first antenna discussed in this dissertation is a dual, triple trident antenna with dimensions 24 mm × 28 mm × 0.785 mm, which will operate from 3 GHz to 12.15 GHz [58]. The first antenna consists of six tridents symmetrical along the vertical direction. The second antenna design is a novel rectangular ring ultra-wideband antenna [59]. Large antennas operate for low frequency, and small antennas work for high frequency. The number of rings increased in wideband antenna to 9 from 4 to check the design methodology. The rectangular ring ultra-wideband antenna has dimensions 24 mm × 26 mm × 1.52 mm. This antenna operates from 3.12 GHz to 12.85 GHz. The third antenna design is an ultra-wideband dual square trident planar antenna. This antenna’s overall size is 26 mm × 24 mm × 1.56 mm [60]. This antenna has impedance bandwidth from 3.65 GHz to 12.50 GHz. The fourth antenna design is an ultra-wideband antenna with a band notch from 5.05 GHz to 5.9 GHz [61]. This antenna consists of two tridents and two split-ring resonators along the microstrip feed line. The overall size of this antenna 26 mm ×24 mm × 1.53mm. Simulations are carried out using the CST microwave studios® to analyze the antenna performance. Experiments are conducted to verify the simulated results using vector network analyzers for impedance and anechoic antenna chamber for radiation characteristics of the antenna. All four antennas are excellent for the wireless device due to their compact size and planar designs.
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Sousa, Jonas Rodrigo da Silva. "Estudo de antenas para comunicação na faixa de subterahertz". Universidade Federal Rural do Semi-Árido, 2016. http://bdtd.ufersa.edu.br:80/tede/handle/tede/766.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The antennas in nano-metric scales are part of a line of research that has been gaining strength in recent years, being the target of numerous studies and publications in several universities in Brazil and around the world. Nano antennas are characterized as a promising new branch in the development of devices capable of being applied in different areas, in addition to communication. Occupying a prominent place in the new era of technologies, the nano antennas, here restricted only to dipole and microstrip, generate enormous expectations about this new revolution, not only between researchers, but also in a part of society. Currently, wireless communications require that radiator devices have wide bandwidth and miniaturization for mobile devices, so this dissertation discusses the potential application of antennas for communications in the frequency range in Terahertz. At these frequencies, there are numerous restrictions on the propagation of signals, so high performance antenna are necessary to allow communication with reduced losses. The purpose of this work is to study some configurations and types of antennas, such as microstrip antenna and dipole antenna, with application in the subterahertz frequency, which can be used, for example, in internal networks, medicine, photovoltaic power generation, spectroscopy, near-field microscopy and high quality images. Some configurations of antennas with various materials for communications in the frequency range will be presented to verify the feasibility of the use of nano dipole antennas and miniaturized microstrip antennas in this type of application. The methodology adopted suggests the comparison of the simulated results, through the software Ansoft HFSS ® and CST Microwave Studio ®, with the results of other published works
As antenas em escalas nanométrica fazem parte de uma linha de pesquisa que vem aumentando nos últimos anos, sendo alvo de inúmeros estudos e publicações. As nanoantenas caracterizam-se como um novo e promissor ramo no desenvolvimento de dispositivos capazes de ser aplicados em diferentes áreas, além da comunicação. Ocupando lugar de destaque na nova era das tecnologias, as nanoantenas, aqui restritas somente as de dipolo e microfita, geram enorme expectativas. Atualmente as comunicações sem fio requer que os dispositivos radiadores possuam uma ampla largura de banda e miniaturização para dispositivos móveis, assim, essa dissertação discute a aplicação potencial de antenas para comunicações na faixa de frequência em Terahertz. Nessas frequências existem inúmeras restrições na propagação de sinais, então antenas com alto rendimento são necessárias para permitir comunicação com perdas reduzidas. A proposta desse trabalho é estudar algumas configurações e tipos de antenas, tais como de antena de microfita e antena dipolo, com aplicação na faixa de frequência em subterahertz, que podem ser utilizadas, por exemplo, nas redes internas, medicina, na geração de energia fotovoltaica, espectroscopia, microscopia de campo próximo e obtenção de imagens de alta qualidade. Serão apresentadas algumas configurações de antenas e com diversos materiais para comunicações na faixa de frequência em questão, para verificar a viabilidade do uso de nanoantenas de dipolo e de antenas de microfita miniaturizadas neste tipo de aplicação. A metodologia adotada sugere a comparação dos resultados simulados, através dos softwares Ansoft HFSS ® e CST Microwave Studio ®, com os resultados de outros trabalhos publicados
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Martinis, Mario. "Développement et caractérisation de métamatériaux pour application en cavité : application à la conception d'antennes compactes". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S107/document.
Testo completoAbstract (sommario):
Cette thèse présente de nouveaux développements pour de petites antennes en cavité. L'objectif principal de la thèse est l'analyse de la performance de la bande passante de ces antennes pour des tailles d'ouverture qui sont petites par rapport à la longueur d'onde en espace libre. Des cavités de formes rectangulaires et circulaires intégrées dans un plan de masse infini et dans des plans de masse de dimensions latérales finies sont examinées en détail. Jusqu'à présent, dans la littérature, le choix pour ces antennes en cavités portait sur des antennes imprimées microruban (patch). L'objet de la thèse est de déterminer si les performances d'antennes en cavité de petite taille peuvent être améliorées et si oui, de quelle façon. A cet effet, nous avons tout d'abord étudié théoriquement, la limite supérieure de la bande passante pour cette configuration particulière en cavité. Nous en avons conclu que les antennes microruban intégrées dans une cavité n'atteignent pas la limite de la bande passante, ce qui est l'un des principaux résultats de la thèse. Les antennes intégrées dans une cavité avec un plan de masse infini ou fini sont ensuite analysées à l'aide de plusieurs modèles de ligne de transmission simples. Le deuxième résultat clé de la thèse un modèle de ligne de transmission spécifique et original qui montre que cette limite sur la bande passante est réellement atteignable. Par conséquent, ce modèle de ligne de transmission devient la base d'une nouvelle conception pour l'antenne en cavité. Enfin, le résultat le plus important de la thèse est la conception concrète de nouvelles antennes en cavité capables d'atteindre la performance maximale en bande passante. D'autres sujets sont abordés sont: i) la comparaison avec des structures à base d'éléments empilés en termes de bande passante, de facilité de fabrication et de coût, ii) l'extension de la limite grâce à l'inclusion de matériaux magnétiques idéaux et conducteurs magnétiques; iii) l'utilisation de la nouvelle structure d'antenne pour la constitution d'un réseau d'antennes compact; iv) les avantages de la nouvelle structure pour la réalisation d'antennes en cavité de tailles vraiment petites pour lesquelles les méthodes classiques ne permettent pas la réalisation d'antennesThis thesis presents new developments in cavity type antennas. The main objective of the thesis is bandwidth performance analysis of antennas in cavities with aperture sizes which are small compared to the free space wavelength. Cavities of rectangular and circular shapes in an infinite and finite ground plane are investigated in detail. So far in the literature, microstrip patch antennas were the antenna of choice for cavity type antennas. The intention of the thesis is to determine if cavity type antennas can be improved and how. To this end, the bound on bandwidth for cavity antennas is investigated theoretically. It is concluded that patch antennas, in fact, do not reach the bound for cavity antennas, which is one of the key results of the thesis. Infinite and finite sized ground plane cavity antennas are further analyzed using several simple transmission line models. The second key result of the thesis is a demonstration that a special transmission line model corresponds to antennas that reach the bound on bandwidth. This transmission line model is the basis to a new cavity antenna design. Finally, the most important result is a practical, physical, design of novel cavity antennas capable of reaching the bandwidth bound. Furthermore, several additional topics are explored; i) A comparison with stacked patches design in terms of bandwidth, ease of fabrication, and cost; ii) The extension of the bound with the inclusion of ideal magnetic materials and magnetic conductors; iii) The new antenna design use in constructing a compact antenna array; iv) The benefits of the new design for constructing small cavity antennas previously not feasible with the classical design
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Li, Hui. "Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96239.
Testo completoAbstract (sommario):
Research on multiple antenna systems has been a hot topic in recent years due to the demands for higher transmission rate and more reliable link in rich scattering environment in wireless communications. Using multiple antennas at both the transmitter side and the receiver side increases the channel capacity without additional frequency spectrum and transmitted power. However, due to the limited space at the size-limited terminal devices, the most critical problem in designing multiple antennas is the severe mutual coupling among them. The aim of this thesis is to provide compact, decoupled and efficient multiple antenna designs for terminal devices. At the same time, we propose a simple and cost effective method in multiple antenna measurement. All these efforts contribute to the development of terminal devices for the fourth generation wireless communication. The background and theory of multiple antenna systems are introduced first, in which three operating schemes of multiple antenna systems are discussed. Critical factors influencing the performance of multiple antenna systems are also analyzed in details. To design efficient multiple antenna systems in compact terminals, several decoupling methods, including defected ground plane, current localization, orthogonal polarization and decoupling networks, are proposed. The working mechanism and design procedure of each method are introduced, and their effectiveness is compared. Those methods can be applied to most of the terminal antennas, reducing the mutual coupling by at least 6dB. In some special cases, especially for low frequency bands below 1GHz, the chassis of the device itself radiates like an antenna, which complicates the antenna decoupling. Thus, we extend the general decoupling methods to the cases when the chassis is excited. Based on the characteristic mode analysis, three different solutions are provided, i.e., optimizing antenna locations, localizing antenna currents and creating orthogonal modes. These methods are applied to mobile phones, providing a more reliable link and a higher transmission rate, which are evaluated by diversity gain and channel capacity, respectively. In order to measure the performance of multiple antenna systems, it is necessary to obtain the correlation coefficients. However, the traditional measurement technique, which requires the phase and polarization information of the radiation patterns, is very expensive and time consuming. In this thesis, a more practical and convenient method is proposed. Fairly good accuracy is achieved when it is applied to various kinds of antennas. To design a compact and efficient multiple antenna system, besides the reduction of mutual coupling, the performance of each single antenna is also important. The techniques for antenna reconfiguration are demonstrated. Frequency and pattern reconfigurable antennas are constructed, providing more flexibility to multiple antenna systems.QC 20120604
Libri sul tema "Antennas"
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Company, Watkins-Johnson, a cura di. Antennas and antenna systems. Palo Alto, CA: Watkins-Johnson Co., 1990.
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Blake, Lamont V. Antennas. 2a ed. Silver Spring, Md: Munro Pub. Co., 1991.
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Fang, D. G. Antenna theory and microstrip antennas. Boca Raton: Taylor & Francis, 2010.
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Fang, D. G. Antenna theory and microstrip antennas. Boca Raton, FL: CRC Press/Taylor & Francis, 2010.
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W, Long Maurice, a cura di. Antennas: Fundamentals, design, measurement. Raleigh, NC: SciTech Pub., 2009.
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Kraus, John D. Antennas. 2a ed. New York: McGraw-Hill, 1988.
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Kraus, John Daniel. Antennas. 2a ed. New York: McGraw-Hill, 1988.
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Kraus, John D. Antennas. 2a ed. New York: McGraw-Hill, 1989.
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M, Weiner Melvin, a cura di. Adaptive antennas and receivers. Boca Raton, FL: Taylor & Francis, 2005.
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ESA, Workshop on Mechanical Technology for Antennas (2nd 1986 Noordwijk Netherlands). Second ESA Workshop on Mechanical Technology for Antennas: Proceedings of a workshop held at ESTEC, Noordwijk, the Netherlands, 20-22 May 1986. Paris: European Space Agency, 1986.
Cerca il testo completoCapitoli di libri sul tema "Antennas"
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Keller, Reto B. "Antennas". In Design for Electromagnetic Compatibility--In a Nutshell, 111–34. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-14186-7_9.
Testo completoAbstract (sommario):
AbstractThis chapter is a brief introduction to antennas and electromagnetic radiation, focusing on antennas for EMC tests. We skip the math intense part around Maxwell’s Equations.The formulas and statements in this chapter apply to the far-field (not the near-field), free-space, matched impedances (of antennas and receiver/transmitter equipment), and matched polarization (of the electromagnetic waves and the antenna polarization).
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Groth, Mateusz, Mateusz Rzymowski, Krzysztof Nyka e Lukasz Kulas. "Reconfigurable Antennas for Trustable Things". In Intelligent Secure Trustable Things, 151–67. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-54049-3_9.
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AbstractIn modern applications, the Internet of Things plays a significant role in increasing the productivity, effectiveness or safety and security of people and assets. Additionally, the reliability of Internet of Things components is crucial from the application point of view, where a resilient and low-latency network is needed. This can be achieved by utilizing reconfigurable antennas to enhance the capabilities of the wireless sensor network (WSN). Additionally, reconfigurable antennas can provide extended functionalities to the Internet of Things. One such aspect of wireless sensing is localization, where objects can be identified and positioned using radio frequency (RF) signals. For this purpose, analysis of spatial diversification of signals can be used by utilizing reconfigurable antennas. This work presents a design of a reconfigurable antenna that is applicable to Internet of Things WSNs and algorithms that utilize the antenna to provide additional localization functionalities.
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Dunlop, J., e D. G. Smith. "Antennas". In Telecommunications Engineering, 212–43. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4899-2929-7_7.
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Wulff, Alex. "Antennas". In Beginning Radio Communications, 45–67. Berkeley, CA: Apress, 2019. http://dx.doi.org/10.1007/978-1-4842-5302-1_3.
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Maqsood, Moazam, Steven Gao e Oliver Montenbruck. "Antennas". In Springer Handbook of Global Navigation Satellite Systems, 505–34. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-42928-1_17.
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Wootton, Cliff. "Antennas". In Samsung ARTIK Reference, 221–27. Berkeley, CA: Apress, 2016. http://dx.doi.org/10.1007/978-1-4842-2322-2_15.
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Balaji, S. "Antennas". In Electromagnetics Made Easy, 619–51. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2658-9_10.
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Dunlop, J., e D. G. Smith. "Antennas". In Telecommunications Engineering, 216–47. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4615-8004-1_7.
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Zhang, Zhiya, Masood Ur-Rehman, Xiaodong Yang, Erchin Serpedin, Aifeng Ren, Shaoli Zuo, Atiqur Rahman e Qammer Hussain Abbasi. "Broadband Antennas". In Wideband, Multiband, and Smart Reconfigurable Antennas for Modern Wireless Communications, 27–71. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-8645-8.ch002.
Testo completoAbstract (sommario):
Apart from the sleeve monopole, this chapter discusses other broadband antennas as well, and the performance evaluation in terms of various measured and simulated parameters is also illustrated. This chapter will help antenna engineers get a better understanding of the antennas discussed and make a comparison with other broadband antennas. The broadband antennas that have been discussed in this chapter include: Low-profile sleeve monopole antenna, Dual-sleeve monopole antenna, Disc-conical sleeve monopole antenna, Wideband with dumbbell-shaped open sleeve antenna, Wideband unidirectional patch antenna with G-shaped strip feed, Wideband folded bowtie antenna with G-shaped strip feed and tuning stubs, Wideband bowtie antenna with inverted L-shaped coupling feed and tuning stubs.
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Kumari, A. "Hard Ferrites for High Frequency Antenna Applications". In Materials Research Foundations, 152–84. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902318-6.
Testo completoAbstract (sommario):
Advances in wireless communication place an increasing number of demands on antenna performance, necessitating the presence of various capabilities in a single device. Reconfigurable antennas are frequently utilized to meet these various application demands within a restricted area. The purpose of this book chapter is to summarize general introduction about hard ferrites, different synthesis methods of ferrite for antenna application and altering functioning of antenna by reconfiguring them by ferrites. Along with this we have also focused on miniaturization and reconfiguration of antennas which is becoming a very important aspect of wireless communication devices. Miniaturization and reconfiguration of antennas involves a deliberate alteration in the form and/or electrical behaviour of the antenna, leading in a change in the antenna's functioning.
Atti di convegni sul tema "Antennas"
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Sulic, E., B. Pell, S. John, Rahul K. Gupta, W. Rowe, K. Ghorbani e K. Zhang. "Performance of Embedded Multi-Frequency Communication Devices in Smart Composite Structures". In ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-402.
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Lately, there has been an increased demand for vehicle manufacturers to incorporate a large number of communication, security, guidance and entertainment devices in their new vehicle models. In recent decades, the list has expanded from the AM and FM radio antennas to include GPS, mobile phone, collision avoidance radar, Digital Radio and Digital TV antennas. In addition, new technologies such as vehicle to vehicle and vehicle to road side communication are being implemented at 5.9 GHz in the next generation of vehicles. In the past the AM/FM antenna was typically a mast antenna protruding from the vehicle’s exterior, recently however, the trend has been to limit the visibility of vehicular antennas as much as possible to improve vehicle design and aerodynamics. This has lead to integration of antennae so that they become a seamless part of the vehicle structure. This paper reports on a parametric study of embedding an antenna in a polymeric composite substrate in relation to several material processing and coating parameters.
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Shah, Hamil, Abdullahi Inshaar, Chengzhe Zou, Shreyas Chaudhari, Saad Alharbi, Asimina Kiourti e Ryan L. Harne. "Multiphysics Modeling and Experimental Validation of Reconfigurable, E-Textile Origami Antennas". In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85603.
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Physical deformation mechanisms are emerging as compelling and simple ways to adapt radio frequency (RF) characteristics of antennas in contrast to digital steering approaches acting on topologically fixed antennas. Concepts of physical reconfigurability also enable exceptional capabilities such as deployable and morphing antenna arrays that serve multiple functions and permit compact transport with ease. Yet, the emergent concepts lack broad understanding of effective approaches to integrate conformal, electrically conductive architectures with high-compliance foldable frameworks. To explore this essential interface where electrical demands and mechanical requirements may conflict, this research introduces a new class of origami-based tessellated antennas whose RF characteristics are self-tuned by physical reconfiguration of the antenna shape. E-textile materials are used to permit large antenna shape change while maintaining electrical conductivity. Dipole and patch antennas are considered as conventional antenna platforms upon which to innovate with the e-textile origami concept. Multiphysics modeling efforts establish the efficacy of foldable antenna geometries for broad tailoring of the RF characteristics. Experiments with proof-of-concept antennas confirm the large adaptability of wave radiation properties enabled by the reconfiguration of the e-textile origami surfaces. The results suggest that e-textile antennas can be integrated into clothing and mechanical structures, providing a non-invasive way of quantifying deformation for a wide range of applications.
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Yoon, Hwan-Sik, e Gregory Washington. "Analysis of Active Doubly Curved Antenna Structures". In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0957.
Testo completoAbstract (sommario):
Abstract Recently, aperture antennas that have the ability to change their reflector shape through the usage of piezoelectric actuators have been studied. The results show that those antennas can exhibit beam steering and beam shaping in the far-field. However, the previous studies have been confined to cylindrical shape antennas. This study examines the use of “doubly curved” antenna structures to achieve better performance in controlling an antenna’s coverage area. The spherical antenna is modeled as a shallow spherical shell with a small hole at the apex for mounting. Following Reissener’s approach, a stress function is introduced and two governing equations are derived in terms of the stress function and the axial deflection. Next, the amount of deflections are evaluated from the calculated stress function and the axial deflection. As actuators, four PZT strip actuators are attached along the meridians separated by 90 degrees respectively. The force developed by the actuators are expanded in Fourier series and fed into the governing equations as boundary conditions at the outer edge. Finally, the Deflection vs. Applied Voltage is calculated analytically and its effect on the far-field radiation is given.
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Wang, C. S., H. Bao e W. Wang. "Coupled Structural-Electromagnetic Optimization and Analysis of Space Intelligent Antenna Structural Systems". In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59306.
Testo completoAbstract (sommario):
For high electromagnetic performances, large space truss antennas should have reflector surface with an extremely high precision. Due to the varied load and some random disturbances, active control strategy is always used in the kind of structure for the precise surface. For the improvement of the electromagnetic performances, an electromechanical synthesis optimization model of space antenna structure systems is developed based on the antenna’s characteristics, which adopts the axial gain of antenna and power consumption of actuators as the objective functions, and structural material strength and actuator’s capability as constraint conditions. The application of model to an 8-m antenna structure demonstrates the potential for significant improvement. The analysis results indicate the benefit of including electrical performance in model for necessary effort for shape control of large space antenna reflectors.
5
Shahanas, K. S., R. Sruthy, K. R. Rahna, M. Sumi e A. I. Harikrishnan. "Review on UHF RFID Tag Antenna". In 2nd International Conference on Modern Trends in Engineering Technology and Management. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.160.42.
Testo completoAbstract (sommario):
This paper presents a comprehensive review of ultra-high frequency (UHF) radio frequency identification (RFID) tag antennas. Due to multiple benefits, RFID technology has supplanted conventional methods of identification like barcodes, magnetic stripe cards, and smart cards. The size of the antenna plays a crucial role in determining the overall dimensions of the RFID tag, making antennas typically low profile and compact. It is acknowledged as an innovative approach for tracking because of its affordable price, passive wireless power transfer capabilities, versatility, and non-line-of-sight communication. UHF RFID tag antennas find widespread use in various applications such as supply chain management, asset tracking, and vehicle identification. The UHF antennas are favoured because they enable simultaneous detection of more tags, provide greater read ranges and faster reading rates, and necessitate fewer antennas than low frequency and high frequency antennas. Establishing the application requirements, choosing the ideal antenna design and substrate material, developing, and optimizing the antenna, manufacturing the antenna, and connecting the antenna to the RFID tag are all essential processes in implementing an UHF RFID tag antenna. This paper will cover the overview UHF RFID tag antenna, few applications, and its limitations.
6
Koukou, Melina, Vasilis Vellikis, Ioannis Varvaringos, Konstantinos Koutropoulos, Ioannis Myrsinias, Despina Ekaterini Argiropoulos, Andronikos Dourmisis et al. "SDR Helix Antenna Deployment Experiment (SHADE) on board BEXUS". In Symposium on Space Educational Activities (SSAE). Universitat Politècnica de Catalunya, 2022. http://dx.doi.org/10.5821/conference-9788419184405.012.
Testo completoAbstract (sommario):
In the field of space travel, space communications has always presented a slew of obstacles and hurdles that must be overcome in order to complete a successful mission. Space limits inside a satellite or spaceship, vast distances between satellites and ground stations, and a phenomenon known as "Faraday Rotation" in the ionosphere are only a few of the most typical issues. Satellite antennas must be small, compact, efficient, and circularly polarized as a result of the aforementioned issues. The helix antenna is an excellent answer for all of the requirements. In this work we develop a deployment and pointing mechanism of a helix antenna operated with software defined radio algorithms. The features of helix antennas are exceptional, and they are especially suitable for satellite communication. Three coaxial cylinders, two stepper motors, one pulley, and one thread make up a deployment-pointing mechanism. The mechanism deploys the antenna along its longitudinal axis and turns it horizontally towards the ground station. During the flight, the antenna is deployed and retracted. Under different positioning situations, the GPS, an altimeter, and a compass calculate the gondola's position in order to rotate the antenna towards the Ground Station and close the communication link. The antenna's rotation mechanism is triggered by the integrated attitude determination and control system algorithms in order to correct the pointing and orientation towards the Ground Station. The antenna uses software defined radio algorithms to achieve weight and volume reductions while maintaining high efficiency and reconfigurability. The experiment includes a high-definition camera that provides real-time information on the antenna's orientation and condition. SHADE's flight on the BEXUS 28/29 balloon resulted in effective deployment and transmission, as well as the ability to receive and decode transmitted packets. The rotating mechanism met the pointing requirements, and all of the sensor's data was correctly saved to our system. Throughout the trip, there were no signs of thermal risk
7
Bossi, D. E., W. D. Goodhue, L. M. Johnson, M. C. Finn, K. Rauschenbach e R. H. Rediker. "Fabrication and enhanced performance of reduced-confinement GaAlAs tapered-waveguide antennas". In Integrated Photonics Research. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/ipr.1990.mi3.
Testo completoAbstract (sommario):
Tapered-waveguide antennas reduce the far-field divergence of beams emitted from integrated-optical waveguides. Previously, we presented preliminary results on reduced-confinement GaAlAs antennas,1 which, unlike horn antennas, are compatible with two-dimensional antenna development. We now report a new fabrication technique that permits improved and reproducible performance of these antennas, and we describe a numerical simulation that allows us to verify and accurately predict performance limitations of reduced-confinement antennas.
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Washington, Gregory. "Active Aperture Antennas". In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0662.
Testo completoAbstract (sommario):
Abstract Recent studies have shown that reflector surface adaptation can achieve performance characteristics on the order of phase array antennas without the complexity and cost. The work proposed in this study develops a class of antennas capable of variable directivity (beam steering) and power density (beam shaping). The actuation for these antennas is employed by attaching polyvinylidene fluoride (PVDF) film to a metalized mylar substrate. A voltage drop across the material will cause the material to expand or contract. This movement causes a moment which causes a moment to be developed in the structure which causes the structure to change shape. Several studies of flexible structures with PVDF films have shown that cylindrical antennas can achieve significant deflections and thereby offer beneficial changes to radiation patterns emanating from aperture antennas. In this study, relatively large curved actuators are modeled and a deflection vs. force relationship is developed. This relationship is then employed in simulations where the far field radiation patterns of an aperture antenna are manipulated.
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Auston, D. H., X. C. Zhang, N. Froberg, B. B. Hu e J. Darrow. "Large Aperture Photoconducting Antennas". In Picosecond Electronics and Optoelectronics. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/peo.1991.wa1.
Testo completoAbstract (sommario):
We describe a novel optoelectronic technique to generate and detect THz electromagnetic waves by using large-aperture planar photoconducting antennas and antenna arrays. This appoach is an effective method of producing directional and steerable sub-millimeter wave pulses.
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James, Sagil, Shubham Birar, Riken Parekh, Kushal Jain e Kiran George. "Preliminary Study on Fractal-Based Monopole Antenna Fabricated Using 3D Polymer Printing and Selective Electrodeposition Process". In ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2901.
Testo completoAbstract (sommario):
Abstract Modern wireless communication industries need high performance antennas having better connectivity, ultra-wide bandwidth, lightweight and miniaturized. The current design and manufacturing process for antennas have several limitations. This study aims to address some of the limitations of designing and fabricating modern radio frequency wireless antennas. The study proposes a combination of fractal-based monopole antenna design followed by fabrication using additive manufacturing and selective electrochemical deposition process. Multiple designs of monopole antennas are compared, and the performance testing showed that the three-dimensional fractal-based antenna design showed the highest performance. The results of this study would be extremely crucial for overcoming challenges of modern antenna technologies.
Rapporti di organizzazioni sul tema "Antennas"
1
Maragoudakis, Christos E., e Edward Rede. Validated Antenna Models for Standard Gain Horn Antennas. Fort Belvoir, VA: Defense Technical Information Center, agosto 2009. http://dx.doi.org/10.21236/ada629345.
Testo completo
2
Lewis, Richard L. Spherical-wave source-scattering matrix analysis of antennas and antenna-antenna interactions. Gaithersburg, MD: National Bureau of Standards, 1995. http://dx.doi.org/10.6028/nist.tn.1373.
Testo completo
3
Ho, Ping-Tong. Reconfigurable Antennas. Fort Belvoir, VA: Defense Technical Information Center, gennaio 1996. http://dx.doi.org/10.21236/ada304993.
Testo completo
4
Long, Stuart A., e David R. Jackson. Millimeter Wave Antennas. Fort Belvoir, VA: Defense Technical Information Center, ottobre 1988. http://dx.doi.org/10.21236/ada201919.
Testo completo
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Boyns, J. JTIDS Shipboard Antennas. Fort Belvoir, VA: Defense Technical Information Center, aprile 1995. http://dx.doi.org/10.21236/ada297554.
Testo completo
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Kramer, B., M. Lee, C. C. Chen, G. Kiziltas, J. L. Volakis e J. H. Holloran. UWB Conformal Antennas. Fort Belvoir, VA: Defense Technical Information Center, luglio 2004. http://dx.doi.org/10.21236/ada425105.
Testo completo
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Farr, Everett G., e Charles A. Frost. Ultra-Wideband Antennas and Propagation. Volume 1: Antenna Design, Predictions, and Construction. Fort Belvoir, VA: Defense Technical Information Center, luglio 1997. http://dx.doi.org/10.21236/ada328786.
Testo completo
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Farr, Everett G., e Charles A. Frost. Ultra-Wideband Antennas and Propagation. Volume 2: Antenna Measurements and Signal Processing. Fort Belvoir, VA: Defense Technical Information Center, luglio 1997. http://dx.doi.org/10.21236/ada328787.
Testo completo
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Frechet, Jean M. Macromolecular Antennas and Photovotaics. Fort Belvoir, VA: Defense Technical Information Center, maggio 2004. http://dx.doi.org/10.21236/ada424130.
Testo completo
10
Bernhard, Jennifer T., e Joshua A. Fladie. Wideband Conformal Antennas and Arrays. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2005. http://dx.doi.org/10.21236/ada443477.
Testo completo