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Aditya, Pradyumna. "Leaky Wave Antenna." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1473414587856344.
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Jeon, Hyung Min. "Compact Leaky Wave Antenna Using Ferroelectric Materials." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1358023409.
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Paaso, H. (Henna). "Direction of arrival estimation algorithms for leaky-wave antennas and antenna arrays." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526220741.
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Abstract The focus of this thesis is to study direction of arrival (DoA) estimation algorithms for reconfigurable leaky-wave antennas and advanced antenna arrays. Directional antennas can greatly improve the spectrum reuse, interference avoidance, and object and people localization. DoA estimation algorithms have also been shown to be useful for applications such as positioning for user tracking and location-based services in wireless local area networks (WLANs). The main goal is to develop novel DoA estimation algorithms for both advanced antenna arrays and composite right/left-handed (CRLH) leaky-wave antennas (LWAs). The thesis introduces novel modifications to existing DoA estimation algorithms and shows how these can be modified for real-time DoA estimation using both antenna types. Three modified DoA estimation algorithms for CRLH-LWAs are presented: 1) modified multiple signal classification (MUSIC), 2) power pattern cross-correlation (PPCC), and 3) adjacent power pattern ratio (APPR). Additionally, the APPR algorithm is also applied to advanced antenna arrays. The thesis also presents improvements to the modified MUSIC and APPR algorithms. The complexity of the algorithms is reduced by selecting a smaller number of received signals from different directions. The results show that the selection of the radiation patterns is very important and that the proposed algorithms can successfully estimate the DoA, even in a real-world environment. Based on the results, this thesis provides a good starting point for future research of DoA estimation algorithms to enhance the performance of future-generation wireless networks and the accuracy of localizationTiivistelmä Tässä väitöskirjassa tutkitaan suunnanestimointialgoritmeja uudelleen konfiguroituville vuotoaaltoantenneille (LWA, leaky wave antenna) ja kehittyneille antenniryhmille. Suuntaavilla antenneilla voidaan parantaa huomattavasti spektrin uudelleen käyttöä ja esineiden ja ihmisten sijaintipaikannusta sekä pienentää häiriöitä. Suunnanestimointialgoritmit ovat myös osoittautuneet hyödylliseksi esimerkiksi seuranta- ja sijaintipaikannuspalvelusovelluksille langattomissa lähiverkoissa. Työn päätavoite on kehittää uusia suunnanestimointialgoritmeja sekä kehittyneille antenniryhmille että vuotoaaltoantenneille (composite right/left-handed (CRLH) LWA). Työssä osoitetaan, miten olemassa olevia suunnanestimointialgoritmeja voidaan muokata uudella tavalla, jotta ne soveltuisivat molemmille antennityypeille reaaliaikaiseen suunnanestimointiin. Vuotoaaltoantennille on kehitetty kolme erilaista suunnanestimointialgoritmia: 1) muunneltu MUSIC- (multiple signal classification), 2) säteilykyvioiden tehojen ristikorrelaatio- (PPCC, power pattern cross correlation) ja 3) vierekkäisten säteilykuvioiden tehosuhdealgoritmi (APPR, adjacent power pattern ratio). APPR-algoritmia on myös käytetty kehittyneelle antenniryhmälle. Työssä esitetään myös parannuksia muunnelluille MUSIC- ja APPR-algoritmeille. Algoritmien kompleksisuutta voidaan pienentää valitsemalla vähemmän vastaanotettuja signaaleja. Tulokset osoittavat, että signaalien valinta on hyvin tärkeää ja ehdotetut algoritmit estimoivat onnistuneesti saapuvan signaalin suunnan todellisessa mittausympäristössä. Yhteenvetona voidaan sanoa, että tämä väitöstyö on hyvä lähtökohta suunnanestimointialgoritmitutkimukselle, jonka tavoitteena on parantaa tulevien sukupolvien langattomien verkkojen suorituskykyä ja paikannuksen tarkkuutta
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Grbic, Anthony. "A novel leaky millimeter-wave linear slot antenna array." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58792.pdf.
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Nevala, J. (Jaakko). "Design and Implementation of Leaky Wave Antenna control circuit." Master's thesis, University of Oulu, 2015. http://urn.fi/URN:NBN:fi:oulu-201504021307.
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Wireless communication research is seeking new methods to increase the performance of the communications systems. Traditional ways to increase the data rate with higher transmission power or smaller cell size of the network have diminishing returns. Adding more transmitter and receiver antennas is a trend in next generation wireless systems. RLWA (Reconfigurable Leaky Wave Antenna) systems have been introduced to be an alternative way of increasing the performance of communications systems. Therefor research of RLWA integration as part of the already working wireless systems is important. This thesis is a design and implementation work of RLWA control circuit. Designed circuit is aimed to be the bridge between the antenna element and WARP (Wireless Open-Access Research Platform). Operation theories of used integrated circuits such as step-up converters, operational amplifiers and digital to analog converters are discussed. Design process of the control circuit is explained in detail. Schematic and PCB (Printed Circuit Board) are designed using Cadsoft Eagle software. Implemented device is using 12 V DC power supply. Antenna input consists of two analog control signals from 10 V to 30 V. Control circuit input consists of two 8 bit digital signals. Transient analysis simulations are included for the designed circuit parts using Matlab and LTSpice software. Implementation of the design is verified in practice with test setup. Measurement results from the test setup are presentedLangattoman tietoliikenteen tutkimus on etsimässä uusia keinoja tiedonsiirtojärjestelmien suorituskyvyn parantamiseen. Tiedonsiirtonopeuden kasvattaminen perinteisillä menetelmillä kuten kasvattamalla lähetystehoa tai pienentämällä verkon solukokoa ei ole enää yhtä tehokasta, koska ylläpitokustannukset kasvavat ja häiriösignaalin taso nousee suhteessa kohinaan. Lähetys- ja vastaanottoantennien lukumäärän lisääminen tulee olemaan yksi käytetyistä keinoista seuraavan sukupolven langattomissa tietoliikennejärjestelmissä. RLWA (Reconfigurable Leaky Wave Antenna) -järjestelmien avulla voidaan toteuttaa vaihtoehtoinen tapa parantaa tiedonsiirtojärjestelmien suorituskykyä. Tämän takia on tärkeää tutkia RLWA:n yhdistämistä jo toimivaan langattomaan järjestelmään. Tässä diplomityössä suunnitellaan ja toteutetaan RLWA:n ohjauspiiri. Suunniteltu piiri toimii siltana antennielementin ja langattoman avoimen kehitysalustan välillä. Työssä tarvittavien integroitujen piirien, kuten jänniteregulaattorin, operaatiovahvistimien ja digitaali-analogiamuuntimien toimintaperiaatteet käydään läpi. Ohjauspiirin suunnittelutyö selitetään yksityiskohtaisesti. Kytkentäkaavio ja PCB (Printed Circuit Board) suunnitellaan käyttäen Cadsoft Eagle sovellusta. Toteutettu laite käyttää 12 V DC virtalähdettä. Laitteen sisääntulo koostuu kahdesta 8 bittisestä digitaalisesta signaalista. Laite syöttää 10–30 V analogista signaalia antennille. Suunnitelluille piirin osille tehtiin simulaatioita käyttäen transientti analyysiä Matlab ja LTSpice ohjelmistoilla. Toteutetun laitteen toiminta varmennetaan liittämällä se osaksi WARP:ia (Wireless Open-Access Research Platform). Koekytkennän mittaustulokset esitellään
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Vourch, Clement J. "Bull's eye leaky wave antenna for terrestrial and space applications." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7708/.
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This work presents the study of Bull's eye antenna designs, a type of leaky wave antenna (LWA), operating in the 60 GHz band. This band emerged as a new standard for specific terrestrial and space applications because the radio spectrumbecomes more congested up to the millimetre-wave band, starting at 30 GHz. Built on existing Bull's eye antenna designs, novel structures were simulated, fabricated and measured, so as to provide more exibility in the implementation of wireless solutions at this frequency. Firstly, the study of a 60 GHz Bull's eye antenna for straightforward integration onto a CubeSat is presented. An investigation of the design is carried out, from the description of the radiation mechanism supported by simulation results, to the radiation pattern measurement of a prototype which provides a gain of 19.1 dBi at boresight. Another design, based on a modified feed structure, uses a microstrip to waveguide transition to provide easier and inexpensive integration of a Bull's eye antenna onto a planar circuit. Secondly, the design of Bull's eye antennas capable of creating beam deflection and multi-beam is presented. In particular, a detail study of the deflection mechanism is proposed, followed by the demonstration of a Bull's eye antenna generating two separate beams at ±16° away from the boresight. In addition, a novel mechanically steerable Bull's eye antenna, based on the division of the corrugated area in paired sectors is presented. A prototype was fabricated and measured. It generated double beams at ±8° and ±15° from the boresight, and a single boresight beam. Thirdly, a Bull's eye antenna capable of generating two simultaneous orbital angular momentum (OAM) modes l = 3 is proposed. The design is based on a circular travelling wave resonator and would allow channel capacity increase through OAM multiplexing. An improved design based on two stacked OAM Bull's eye antennas capable of producing four orthogonal OAM modes l = (±3,±13) simultaneously is presented. A novel receiving scheme based on discretely sampled partial aperture receivers (DSPAR) is then introduced. This solution could provide a lower windage and a lower cost of implementation than current whole or partial continuous aperture.
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Al, Noor Asif. "A broadband fixed-beam leaky-wave antenna based on transformation electromagnetics." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59555.
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A broadband fixed-beam leaky-wave antenna is presented in this thesis. The proposed antenna consists of a graded dielectric superstrate placed on top of a closely-spaced thin slot array. The graded dielectric superstrate is designed using transformation electromagnetics to couple the radiation from underlying leaky slot-line into free space. Wave propagation in graded dielectric media, properties of leaky-wave antennas, and conformal transformation electromagnetics have been explored prior to the design. The behaviour of the proposed antenna has been subsequently improved through developing a technique that exploits transformation electromagnetics. The technique adjusts the discrepancy in phase produced as a result of coordinate stretching at the boundary of transformed medium. Full-wave simulations are carried out to demonstrate the performance of the leaky-wave antenna. Broadband radiation characteristics are achieved from the antenna with peak radiation around 33⁰, 30% side-lobe level, 53% back-lobe level, 30.6⁰ beamwidth, and 11.8 directivity. Such performance makes the antenna suitable for planar applications where a fixed oblique beam is required over a broad bandwidth.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Wang, Jiahui. "High-K Material Based Leaky-wave Antenna Design, Implementation, and Manufacture." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347582062.
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Loukos, Georgios I. "Propagation characteristics of cylindrical frequency selective guides." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/32321.
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Recent experimental investigation on FSS arrays forming waveguides (FSGs) and horns showed that incident electromagnetic energy can be guided and radiated at specific frequencies. This thesis aims to provide the theoretical understanding of the waves propagating inside a cylindrical FSS waveguide. With immediate applications on horn antennas the research deals with cylindrical guides, made entirely from double periodic arrays. The theoretical analysis begins as a standard electromagnetic boundary value problem. The formulated system of algebraic equations is solved either for the complex propagation constant, by an iterative procedure or, for the fields. The analysis makes use of the Floquet modal expansion, the current representation as a set of sub-domain basis functions and the Method of Moments. Initially, the thesis is concerned with single periodic structures, which is a special case to the analysis. The efficiency of the model to provide stable and valid results is examined. Next the elements are finite dipoles. The effects of the dipole resonance to the propagating and radiating characteristics of the FSS is closely investigated. Other aspects include the effects of the periodicity and the element size. The investigation concludes with an FSG with square loop elements. Validation of the results for some designs is made by comparison with measured data.
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Corwin, Michael Thomas. "Inductively Loading a Half Width Leaky Wave Antenna to Control the Main Beam Direction." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1342464210.
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Roig, Parras María [Verfasser], and Rolf [Akademischer Betreuer] Jakoby. "Tunable Metamaterial Leaky Wave Antenna based on Microwave Liquid Crystal Technology / María Roig Parras. Betreuer: Rolf Jakoby." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1112044485/34.
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Cox, Gavin J. "Techniques for pattern control of a dielectric rod antenna suitable for use in mobile communications." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/12693.
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This thesis describes the development of antennas suitable for mobile coinmunication systems based on a dielectric rod antenna fed from circular waveguide. Pattern control of the antenna is implemented using a combination of Frequency Selective Surface (FSS) elements and metallic endcaps placed on the antenna Both linear and circular polarised feeds have been made for these antennas to ensure they are suitable for a wide range of applications. The suitability of the dominant and next, higher order, waveguide mode were investigated and conclusions drawn as to their suitability for this type of antenna. The antennas were extensively modelled using a commercial TLM based solver and the results of these simulations were compared to the comprehensive set of antenna pattern measurements and S-parameter measurements obtained for the prototype antennas.
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Fuscaldo, Walter. "Advanced radiating systems based on leaky waves and nondiffracting waves." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S015/document.
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La focalisation du champ électromagnétique dans les zones de champ proche et lointain est un sujet de forte actualité pour l'imagerie médicale et la radiométrie des microondes jusqu'aux ondes millimétriques. Dans ce cadre, la théorie des ondes de fuite est un formalisme élégant qui permet de décrire d'une même façon les problèmes radiatifs en champ proche et en champ lointain des microondes aux fréquences optiques. Dans cette thèse, on utilise la polyvalence de la théorie des ondes de fuite pour développer des systèmes rayonnants complexes afin de contrôler les caractéristiques radiatives en champ lointain aux fréquences submillimétriques et pour focaliser la radiation électromagnétique en champ proche aux fréquences millimétriques. Ainsi, l'utilisation de matériaux uniques comme le graphène et les cristaux liquides ont été considérés pour la conception des antennes à ondes de fuite, en obtenant des résultats très intéressants en termes de reconfigurabilité, d'efficience et de directivité. Dans ce contexte, une analyse théorique originale a fourni de nouvelles formules pour l'évaluation des caractéristiques radiatives (c.à.d. la largeur de faisceau, le niveau des lobes secondaires, etc.) des antennes à ondes de fuite. En effet, la largeur du faisceau de ces antennes est, jusqu'à présent, estimée au moyen des formules proposées pour la première fois dans les années '60 par Prof. Arthur A. OLINER. Ces formules ne tiennent en compte ni de la longueur de l'antenne (sauf pour des cas très particuliers), ni du rayonnement longitudinal, elles ne permettent donc pas une évaluation rigoureuse.En complément à la reconfigurabilité en champ lointain, les ondes de fuite offrent aussi la possibilité de focaliser la radiation en champ proche. Dans ce cas, on voit que les ondes de fuite peuvent être utilisées d'une façon efficace pour générer des faisceaux non diffractifs de Bessel à travers des systèmes rayonnants à bande étroite aux ondes millimétriques. De plus, le caractère non diffractif des faisceaux de Bessel peut aussi être utilisé pour générer des impulsions très localisées (comme les solitons en optiques) à travers la superposition continue des faisceaux de Bessel sur une large bande de fréquence. Dans ce cadre, une nouvelle formulation a été développée afin de comprendre les limitations physiques et technologiques concernant la génération des impulsions non diffractives et non dispersives, c.à.d. les X-waves. Les résultats ont montré qu'un type de systèmes rayonnants à large bande, notamment les antennes RLSA (en anglais « Radial Line Slot Array »), semblent très favorables pour la génération des X-wavesIn recent years, microwave, millimeter-wave, and THz applications such as medical and security imaging, wireless power transfer, and near-field focusing, just to mention but a few, have gained much attention in the area of ICT due to their potentially high social impact. On one hand, the need of highly-directive THz sensors with tunable radiating features in the far-field region has recently boosted the research activity in the design of flexible, low-cost and low-profile devices. On the other hand, it is of paramount importance to focus energy in the near-field region, and thus the generation of limited-diffraction waves in the microwave and millimeter-wave regime is a topic of recent increasing interest. In this context, leaky-wave theory is an elegant and extremely useful formalism which allows for describing in a common fashion guiding and radiating phenomena in both the near field and the far field, spanning frequencies from microwaves to optics passing through THz. In this PhD thesis we aim to exploit the intrinsic versatility of the leakywave approach to design advanced radiating systems for controlling the far-field radiating features at THz frequencies and for focusing electromagnetic radiation in the near field at millimeter waves. Specifically, the use of relatively new materials such as graphene and liquid crystals has been considered for the design of leaky-wave based radiators, achieving very promising results in terms of reconfigurability, efficiency, and radiating capabilities. In this context, an original theoretical analysis has provided new general formulas for the evaluation of the radiating features (e.g., half-power beamwidth, sidelobe level, etc.) of leaky-wave antennas. Indeed, the current formulations are based on several simplifying hypotheses which do not allow for an accurate evaluation of the beamwidth in different situations. In addition to the intriguing reconfigurable capabilities offered by leaky waves in far-field applications, interesting focusing capabilities can be obtained in the near field. In particular, it is shown that leaky waves can profitably be used to generate limited-diffraction Bessel beams by means of narrow-band radiators in the microwave range. Also, the use of higherorder leaky-wave modes allows for achieving almost the same performance in the millimeter-wave range, where previous designs were subjected to severe fabrication issues. Even more interestingly, the limited-diffractive character of Bessel beams can also be used to generate limited-diffraction pulses as superpositions of monochromatic Bessel beams over a considerable fractional bandwidth. In this context, a novel theoretical framework has been developed to understand the practical limitations to efficiently generate limited-diffraction, limited-dispersion pulses, such as X-waves, in the microwave/millimeter-wave range. As a result of this investigation, a class of wideband radiators has been thoroughly analyzed, showing promising capabilities for the generation of both zeroth-order and higher-order Xwaves. The latter may pave the way for the first localized transmission of orbital angular momentum in the microwave range
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Булашенко, Андрій Васильович, Андрей Васильевич Булашенко, and Andrii Vasylovych Bulashenko. "Аналіз антени витікаючої хвилі." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47186.
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Більшість публікацій з антен витікаючих хвиль відносяться до періодичних
випромінюючих структур. Хоча існує багато робіт з цих типів антен, але дослідження
та розробки в цій області тривають. Удосконалюються методи моделювання та
технології виготовлення, також розширюється область використання таких антен.
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Decle, Colin Daniel. "Novel metamaterial structures for microwave component and circuit performance enhancements." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/novel-metamaterial-structures-for-microwave-component-and-circuit-performance-enhancements(c446a06c-7a46-4368-801c-76230eb0a104).html.
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In the thesis presented, three novel uni-planar left handed transmission lines based on Complementary Split Ring Resonators (CSRR) and Complementary Spiral Resonator (CSR) metamaterial particles are proposed for the first time and successfully applied for the performance enhancement of conventional coupled line filters and the design of a full scan leaky wave antenna. Based on the implementation of Complementary Split Ring Resonators (CSRR) a fully planar Composite Right left handed transmission line (CRLH-TL) plus a Dual Composite Right Left Handed transmission line (D-CRLH-TL) are proposed, designed and studied. The CRLH transmission line is realized loading a microstrip host line with CSRR metamaterial particles and capacitive gaps on the conductor strip of the line, while the D-CRLH transmission line is built bridging the capacitive gaps between the CSRR's with inductive connections to induce dual propagation properties in the structure. A further performance enhancement is achieved by a second proposal based on the implementation of Complementary Spiral Resonators (CSRs). The studies applied to the structure reveal that conditions for D-CRLH propagation are created in a transmission line composed only by CSR metamaterial resonant particles as the result of the unique electromagnetic properties acquired by the CSRs etched on the conductor line of a microstrip waveguide. The CSRR/CSR based D-CRLH transmission lines proposed are applied in the design of two enhanced coupled line filters. The implementation is possible for the first time in this work as result of the highly versatile layout features of the left handed transmission lines proposed which among other important geometrical features, allows couplings in both sides of the structure. Enhanced filtering features are reached by the metamaterial based coupled line filters proposed in terms of selectivity and size reduction in comparison with conventional coupled line filters. In the case of the CSRR loaded metamaterial coupled line filter a size reduction of 49% is achieved compared with a filter of similar performance. A further enhancement is reached by the second coupled filter proposed based on CSR metamaterial resonant particles. The CSR coupled filter proposed reach a roll off rate improvement of 8 dB/GHz and size reduction of 43% in comparison with a conventional coupled line filter of the same order. When this is compared against a conventional coupled line filter of similar performance but higher order, a remarkable size reduction of 77% is achieved by the proposed CSR coupled line filter. Finally, the CSR loaded D-CRLH transmission line is applied in the design of a fully planar leaky wave antenna. Using the CSR structures etched on the conductor line of a microstrip as part of the radiation mechanism altogether with the D-CRLH propagation features of the structure. A full scan radiation pattern is created with backward, forward and broadside radiation as result of the left handed propagation band, right handed propagation band and the balanced transition between them. Two leaky wave antennas are designed to operate at the centre frequencies of 12.5GHz and 6.0GHz. In order to corroborate the performance the CSR D-CRLH leaky wave antenna operating at 6.0GHz is fabricated and measured showing a scanning range of 30 deg with a maximum gain of 13.2 dBi.
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Javora, Petr. "Návrh planárních anténních struktur z metamateriálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218023.
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The thesis deals with basic principles of metamaterials, which exhibit unusual properties in microwave applications (e.g., negative permittivity and permeability). Different type of metamaterial antennas and parameters of such antennas are described in the thesis.
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Noujeim, Karam M. "Fixed-frequency beam-steerable leaky-wave antennas." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0016/NQ45831.pdf.
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Feresidis, Alexandros. "Broadband high-gain planar leaky-wave antennas." Thesis, Loughborough University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416689.
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茂幸, 西村, and Shigeyuki Nishimura. "遮断TEおよびTMモードを用いた右手/左手系複合導波管の伝送・放射特性." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097319/?lang=0, 2018. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097319/?lang=0.
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本論文では，遮断周波数以下のTE・TMモードを利用した右手/左手系複合円筒導波管および方形導波管を提案する．この提案したCRLH導波管にスリットまたはスロットを設けることで構成された導波管型漏洩波アンテナの放射特性について述べている．最後に，CRLH導波管を試作し解析結果と実験結果の比較を行うことで，CRLH方形・円筒導波管の構成法の有用性を明らかにする．This paper proposes a composite right/left-handed cylindrical and rectangular waveguides using the cutoff TE and TM modes. The CRLH waveguides can be successfully applied to radiation characteristics of leaky-wave antenna by setting slits or slots. Finally, usefulness of the proposed CRLH waveguides is verified by comparison between the calculated and the measured values.
博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
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Zhang, Qiang. "Étude de la propagation et du rayonnement pour des applications au voisinage du corps humain." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS408.
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Le vieillissement de la population et la hausse des coûts des soins médicaux ont engendré de nombreuses innovations dans le domaine de santé. L'une d’elles consiste à utiliser des capteurs sans fil autour du corps humain pour surveiller les signaux vitaux du patient. Le premier objectif de cette thèse est d’améliorer la sécurité des communications entre les capteurs sur le corps humain, grâce à un nouveau mécanisme de transmission utilisant la peau comme support de propagation de l’onde électromagnétique. La méthode de résonance transverse (TRM) est utilisée pour analyser les modes existants dans le modèle du corps humain. Les capacités de confinement ainsi que les pertes de propagation sont étudiées pour des fréquences jusqu’à 60 GHz. Le code développé d’analyse de la dispersion basé sur TRM constitue l’essentiel du travail de cette thèse et est également utilisé pour le second objectif de cette thèse. Une autre innovation dans le domaine médical concerne la surveillance sans contact et sans capteur utilisant des techniques radars Doppler. Les antennes à ondes de fuite sont de bonnes candidatures grâce à leur balayage du faisceau en fonction de la fréquence. Un balayage rapide est souhaité afin de couvrir une large plage angulaire avec une bande de fréquence limitée. Par conséquent, une structure guidante hautement dispersive est typiquement requise pour ce type d’antenne. Ainsi, une procédure originale de conception basée sur le code TRM est proposée pour augmenter la dispersion de la structure guidante imprimée à l’aide de la métasurface. En utilisant cette dispersion améliorée, une antenne périodique à ondes de fuite est conçue et simulée dans la bande des 60 GHzThe aging of population and the increase in medical costs have brought a lot of innovations in the medical domain. One of them is the use of wireless sensors that are located in, on, or around the human body to monitor patient’s physiological signs. Due to the nature of the transmitted data, high data security is one of the most essential requirements in the system. The first objective of this thesis is to improve the communication security between on-body sensors with a novel transmission mechanism that uses human skin as a transmission medium and confines the surface-wave signal inside the skin. Transverse resonance method (TRM) is used to numerically analyze existing modes within the human body model. Confinement capabilities as well as propagation losses are investigated for frequencies up to 60 GHz. It should be noted that the developed TRM-based dispersion analysis code is the core work of this thesis and is used throughout all the main analysis in this thesis. Another innovation in the medical domain can be referred to the non-contact sensor-less remote medical monitoring using Doppler radar. Leaky-wave antennas are good candidatures for such applications due to their frequency-depending beam scanning properties. A fast scanning is desired in order to cover a large angular range with a given operation frequency bandwidth. Consequently, in the second part of this thesis, an original TRM-procedure-based design is proposed to increase the frequency dispersion of the guiding structure, which uses a grounded dielectric slab covered by a metasurface. Using this enhanced dispersion, a periodic leaky-wave antenna is designed and simulated in the 60 GHz band
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Rahman, Atiqur. "Composite Right/Left-handed transmission line based leaky-wave antennas." Thesis, Queen Mary, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528386.
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Dahlberg, Oskar. "Low-dispersive Leaky-wave Antennas: A Viable Approach for Fifth Generation (5G) mmWave Base Station Antennas." Thesis, KTH, Elektroteknisk teori och konstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244458.
Full textAbstract:
In this work, a method to achieve reduced beam-squint in fully metallic leaky-wave antennas is proposed and its applicability for high frequency, high gain, base station antennas in future communication networks is indicated. The antenna is built in gap waveguide technology, where the fundamental mode is allowed to leak by removal of one of the waveguide walls. The leakage is varied along the structure for reduced side lobes and a stable radiation pattern is obtained by coupling the leaked energy from the waveguide through a dispersive prism-lens. The gap waveguide is formed as a groove, sided by three rows of a glide-symmetric holey EBG-structure on one side, suppressing propagation of waves in that direction, and one row of vertical square pins, with tailored heights for optimal leakage, on the other. Beyond the single row of tailored pins, a prism-lens is placed. The prism lens is made of multiple rows of equally spaced and dimensioned, vertical square pins. The dispersive nature of the TE10-mode inside the waveguide is canceled by the oppositely dispersive prism-lens and a stable radiation beam (<1 degree beam-squint) is achieved over a 20% bandwidth. Two antennas are realized, both operating with a center frequency of roughly 60 GHz. The first design is optimized for single-beam operation such that the achieved efficiency is close to 90% across the band and the side lobe levels are below -20 dB. The second design is optimized for dual-beam operation such that two highly directive beams can be obtained, simultaneously or separately. The second design is placed in a 1D-array configuration for electrical beam-steering in one plane, and beam-switching in the orthogonal plane. The two antennas are simulated using CST Microwave Studio.I det här arbetet föreslås en metod för att reducera skanningen av strålnings-riktningen i helt metalliska läckande-vågantenner. Dess applicerbarhet till hög-frekventa, direktiva, basstationsantenner i framtida kommunikationsnätverk är indikerad. Antennen består av en "gap"-vågledare, där den fundamentala moden tillåts läcka genom att den ena sidoväggen tagits bort. Läckaget varieras längs strukturen för att minska sidlobs-nivån och ett konstant strålningsfält uppnås genom att låta den läckta energin brytas genom en dispersiv prism-lins. Vågledaren formas som en fåra, brevid vilken, på ena sidan, tre rader av glidsymmetriska håliga EBG-strukturer placeras för att undertrycka propagering av vågor i den riktningen, och på andra sidan, en enstaka rad av vertikala, fyrkantiga, pinnar placeras, vilkas höjd är skräddarsydd för optimalt läckage. Bakom den enstaka raden med pinnar placeras prism-linsen. Linsen består av flera rader av lika stora, jämnt fördelade, vertikala fyrkantiga pinnar. Frekvensberoendet hos den fundamentala TE10-moden i vågledaren motverkas av det omvända frekvensberoendet i linsen och ett stabilt strålningsfällt (<1 grad skanning) uppnås med 20% bandbredd. Två antenner realiseras, båda med centerfrekvensen 60 GHz. Den första designen är optimerad för en enkel stråle, så att nästan 90% effektivitet och mindre än -20 dB sidlober uppnås över hela bandet. Den andra designen är optimerad för att tillåta två direktiva strålar, samtidigt eller enskilt. Den andra designen staplas också för att forma en 1-dimensionell gruppantenn, vilket tillåter elektrisk utstyrning i ett plan, och strålningsväxling i det ortogonala planet. De två antennerna simuleras med hjälp av CST Microwave Studio.
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Hamilton, Dean P. "Novel dispersion representation of rectangular dielectric guides with application to leaky-wave antennas." Thesis, University of Warwick, 2007. http://wrap.warwick.ac.uk/36671/.
Full textAbstract:
A novel method for graphically and mathematically representing the dispersion characteristics of electromagnetic dielectric structures is presented. The method has been used to develop closed-form formulas to find the longitudinal propagation constant and useful frequency range for a number of popular rectangular dielectric waveguide types. These formulas are presented in terms of their material dependency and are guide size and operating frequency independent. Their form is so trivial that these characteristics can now be found in just a few seconds using a basic calculator, yet still with second order accuracy. In addition, improvements have been made to a number of well-known formulas normally associated with periodic grating leaky-wave antennas. These improvements allow the width of the metal strip grating to be taken into consideration to derive the correct main beam angle, array factor pattern and grating limits. Previously, the grating width was neglected by the formulas and the resulting error was unacceptably high.
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Ma, Lizhuang. "The analysis of inset dielectric guide and its application in leaky wave antennas." Thesis, University of Bath, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328570.
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Hong, Wanchu, and 洪萬鑄. "Broadband Leaky-Wave Antenna." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/43422737599150170394.
Full textAbstract:
博士國立交通大學
電信工程系
91
This thesis proposes the design methodology of broadband leaky-wave antennas. To exploit fully the broadband feature of these broadband leaky-wave antennas, also presented is the design method of the novel broadband planar balun used to excite the first higher order leaky mode. First, an inverted balanced microstrip line structure is proposed. This inverted balanced microstrip line structure is developed from the balanced microstrip line. The position of the positive strip on the upper substrate side is exchanged with that of the negative strip on the lower substrate side by the method proposed in this thesis. The measured return loss is observed to be better than -10dB over a frequency range extending from DC up to 18.6 GHz or from 2.8 GHz up to 40 GHz depending on the different design parameters. United with the balanced microstrip line, this inverted balanced microstrip line can be used to form into a pair of broadband baluns. Using this broadband balun can realize a broadband leaky-wave antenna. Secondly, based on the characteristics of the first higher order leaky-mode for the microstrip antennas, this thesis proposes a novel scheme for the empirical design of broadband tapered microstrip leaky-wave antennas. This scheme is demonstrated to be able to explain and approximately model the radiation characteristics of a linearly tapered leaky-wave microstrip antenna. Also presented is the broadband feeding structure that uses the balanced and the inverted balanced microstrip lines to form two pairs of broadband baluns. The balun on the upper substrate side feeds the microstrip antenna, while the one on the lower substrate side directly connects with the ground plane of the microstrip antenna. The measured return loss of the back-to-back feeding structures has a VSWR£ 2 from 2.2 GHz to 18.6 GHz. The measured bandwidth of the tapered microstrip leaky-wave antenna has a VSWR£2 from 7 GHz to 16.4 GHz, yielding a relative bandwidth of 2.34:1, more than an octave. Another example is the design of the millimeter-wave broadband tapered microstrip leaky-wave antenna array of 1´4 elements. The measured bandwidth of this millimeter—wave broadband tapered microstrip leaky-wave antenna array with 1´4 elements for a VSWR£ 2 is from 13.3 GHz to 35 GHz. With a straight profile, the broadband tapered microstrip leaky-wave antenna consumes area. To design a more compact broadband antenna, the tapered microstrip antenna is curled to save area. Presented is a compact broadband tapered microstrip leaky-wave antenna with a curled profile that has a bandwidth of more than 2.3:1 for a VSWR£ 2. Finally, proposed is a single-conductor strip antenna with only a single-conductor strip on a substrate without any practical ground plane. By using the full-wave integral equation method, the first higher order leaky mode of this single-conductor strip structure is investigated and found to possess a broadband radiation regime. To excite this first higher order leaky mode, a broadband planar balun is developed from the balanced microstrip lines and the inverted balanced microstrip lines. Like the feeding structure of broadband tapered microstrip leaky-wave antenna, the balun on the upper substrate side feeds the strip antenna with an offset from the edge, while the positive and negative balun strips on the lower substrate side are directly interconnected and returned back to the original ground plane of the microstrip line.Both the numerical simulation and the measurement data are presented. This single-conductor strip leaky-wave antenna has a bandwidth of 2.34:1 (from 6.55 GHz to 13.75 GHz) for a VSWR*2. Owing to the particular characteristics of its normalized phase constant, this single-conductor strip leaky-wave antenna has a fixed mainbeam radiation pattern in the endfire direction. As a broadband leaky-wave antenna, the length of this single-conductor strip leaky-wave antenna is much shorter than that of the tapered microstrip leaky-wave antenna.
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Cheng, Chi-Sheng, and 陳智聖. "Leaky Wave Antenna Array Synthesis." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/37025591637408899784.
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碩士國立交通大學
電信工程研究所
84
Part I of the thesis develops a visual C++ computer program for a linear antenna array synthesis from continuous aperture line sources to discrete antenna array. This program is intended for a linear leaky-wave antenna synthesis. Thisarray synthesis produces a desired radiation pattern with all sidelobes depressed at arbitrary degree. The approach is illustrated by 2 examples: 1) a 30 dBTaylor pattern, modified so that the innermost fivesidelobes on one side ofthe main beam are down 40 dB and 2) Beginning with a Taylor pattern which is 20/20, to produce a symmetrical sum patternwith the four innermost pairs of sidelobes at 30 dB, the next four pairs at 15 dB. Part II of the thesis describesa new GaAs MMIC LNA design. A two stage new GaAs MMIC low noise feedback amplifier has been developed with nominal 20 dB gain，2:1 VSWR 1.6 dB noise figure over the 2-3 GHz band. The design approach integrates all the internal bias circuits, matching circuits, feedback networks, the individual active and passive elements into a chip area of 1100 by 1700 um2.
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Chen, Zhi-Hao, and 陳志豪. "The slotline leaky wave antenna." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/21742959700131085486.
Full textAbstract:
碩士國立交通大學
電信工程系所
96
In general , the leaky wave antenna has many advantages such as low cost, frequency scaning, and high gain. The relation of the propagation characteristics of the slotline first higher mode and the higher order mode of dielectric slab are presented in detail in this paper. It is found that the first higher order mode of slotline will be formed the characteristics of the higher order mode of dielectric slab when the width of slotline approachs to zero. Dependence of the propagation characteristics on structural parameter are analyzed. Two different widths of slotline strcture will be excited by feeding the slotline with a microstrip-to-CPW transition. The reason for this feeding is to make antenna broadband. Experimental results show good agreement with our numerical results, and also confirm the existence of the slotline first higher order mode.
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Nien-An, Kao, and 高念安. "Active Aperture-Coupled Leaky-Wave Antenna." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/86577771140409809941.
Full textAbstract:
碩士國立交通大學
電信工程系
87
This thesis will investigate the active aperture-coupled leaky-wave antennas and the multi-beam aperture-coupled leaky-wave antenna, including design, fabrication and measurement. To excite the microstrip first higher mode, the aperture-fed structure is utilized and a sequence of covered wire is added in the center of this antenna to suppress the dominant mode. The leaky-wave antenna offers beam-steering capability, high gain and narrow main beam. In addition, the aperture-fed structure reduces the circuit size and offers an excellent shielding between active and radiation elements. We produce two kinds of active aperture-coupled leaky-wave antennas-side-fed with a single main beam and center-fed with a dual-beam. The side-fed one provides a 16°scanning angle in H-plane from 8.97 GHz to 9.5 GHz and its maximum EIRPs are 21.98±1.59 dBm. The center-fed one provides a 20°scanning angle in H-plane from 8.97 GHz to 9.5 GHz and its maximum EIRPs are 18.56±0.33 dBm for the right beam and 18.9±0.13 dBm. Theses antennas are suitable for active phase antenna array applications or other microwave transceiver system. On the other hand, we utilized the aperture-fed leaky-wave antenna to develop a multi-beam antenna. Its transmitting and receiving radiation patterns are observed their scanning angles as 22°and 16°~18°respectively. This antenna has a developmental potential in transmit/receive modules such as smart antenna systems because both modules employ use only one antenna.
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Wang, Chien-Jen, and 王健仁. "Nonel Active Leaky-Wave Antenna and Commercial Chip Antenna." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/37998832448944644458.
Full textAbstract:
博士國立交通大學
電信工程系
88
This thesis consists of two parts: The development of active frequency-scanning leaky-wave antennas (LWA) and compact microstrip chip antennas. In the first part of the dissertation, three types of the microstrip active frequency-scanning leaky-mode antennas that employ the first higher order mode (the space wave) of odd symmetry in their leaky wave region are presented. In order to excite the first higher order mode, the antennas are fed asymmetrically. These antennas includes the topologies of leaky-wave antenna (LWA) arrays, a two-terminal feeding LWA and a single feeding LWA integrated with a self-oscillating doubler. The antenna arrays are integrated one, two and four microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Using the symmetric configuration of this leaky-wave antenna array not only can effective reduce the reflected wave coming from the open end of a finite-length LWA, but it also can increase the power gain. A two-terminal feeding LWA is integrated with a varactor-tuned HEMT VCO. This design creates a dual-beam radiation pattern and has the advantages of the double scanning covered region and the suppression of the reflected wave. A new method which can enhance the scanning angle and elevate the operating frequency for the active LWA is proposed. We demonstrate an asymmetrically feeding LWA integrated with a self-oscillating doubler on a RT/Duriod substrate. The self-oscillating doubler generates the signal source at the second-harmonic frequency. The operating frequency 2FX (the second harmonic frequency) and the double frequency variation 2ΔFX are twice ΔFX at the fundamental band FX . This feature, combined with the advantage of no external injection power, is useful for millimeter-wave applications of the LWA and to obtain a wider scanning angle. In the second part of the dissertation, a new design of miniaturized microstrip helical antennas is proposed for the mobile communication. The antenna-size reduction is achieved by folding the microstrip line around a substrate. We use the RT-Duriod microwave substrate, the dielectric constant = 10.2 and the height H = 25 mil to fabricate a small microstrip monolithic antenna for the PCS and cellular phones. For the other sample, we use the Low Temperature Co-fired Ceramic (LTCC) technology to fabricate a compact dual-band chip antenna. We have carried out experimental studies on these antennas, which have the large bandwidth and the multiple frequency resonant bands. The chip antenna is suitable for the applications of the wireless network communication and the bluetooth system. In order to increase the resonant bandwidth, the antennas support the helical mode and the monopole mode. The radiation pattern in the E plane of the antenna is quasi-omnidirectional and the characteristic is like as the monopole.
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Chen, Hung-Jen, and 陳鴻仁. "Design of Active Leaky Wave Antenna Arrays." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/12883577425856934540.
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碩士國立交通大學
電信工程系
88
In the recent year, the active antenna has been used widely. In this paper, we will discuss the active antenna array and the measurement method. Active antenna is implement by combing an oscillator and the microstrip leaky-wave antenna. Also, we inject one signal into the oscillator array to ensure the frequency of array antenna is the same.
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Chiu, Chien-Chih, and 邱建智. "Design of Planar Leaky-Wave Retrodirective Antenna Arrays." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/07551022210589534094.
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碩士國立交通大學
電信工程系
88
A two-dimensional Van Atta retrodirective reflector based on the microstrip leaky-wave antennas was designed in this thesis. Planar structure makes this reflector low cost and low profile. Along with the reflector’s property of being able to reflect high fields toward the source point over a wide range of incident angles makes it very suitable for applications in intelligent vehicle highway systems (IVHS). Using the leaky-wave antenna as the basic constructing unit has the advantage of avoiding complex routing of the connecting network commonly encountered in two-dimensional retrodirective array. An eight-element leaky-wave retrodirective array was designed and measured in this thesis. An approximate method associated with the re-radiated and scattered principles of the reflector is presented at X band for the purpose of understanding and designing the reflector. The total reflected field from the reflector is separated into two primary parts, the re-radiated field from the leaky-wave antennas and the scattered field from the metal ground plane. The re-radiated field is calculated by using waveguide model together with the image theory; the scattered field from ground plane is analyzed by the physical optics (PO) method. The experimental results show that both in the E-plane and H-plane the array has a high reflected field within 10dB down from that of a flat metal plate over a range of more than 230 degrees in the E-plane and 110 degrees in the H-plane.
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Su, Ching-Chih, and 蘇敬智. "Wideband Microstrip Leaky-Wave Antenna for 4G LTE." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/n348tq.
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碩士國立臺北科技大學
電子工程系研究所
105
This paper describes a broadband microstrip leaky wave antenna for 4G LTE frequency bands : LTE 700 MHz、GSM 850 MHz、900 MHz、LTE 1500 MHz、1700 MHz、GSM 1800 MHz、1900 MHz、UMTS and LTE 2500 MHz、3500 MHz . The proposed antenna covers the frequency range from 0.7 GHz to 4 GHz for future frequency band expansion. The antenna design uses half-width microstrip structure to replace the traditional complex full width structure requiring differential excitation circuit. This proposed half width structure consists of long rectangular microstrip with short circuits formed by a series of metal via holes between the microstrip and the ground plane periodically. The measurement results show that maximum peak realized gain of 7 dBi is achieved. Measured return loss of antenna is larger than 6 dB in the operating bandwidth, and the low frequency band is relatively broad compared to the conventional microstrip leaky wave antenna.
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Alibakhshikenari, M., B. S. Virdee, M. Khalily, P. Shukla, C. H. See, Raed A. Abd-Alhameed, F. Falcone, and E. Limiti. "Beam-scanning leaky-wave antenna based on CRLH-metamaterial for millimeter-wave applications." 2019. http://hdl.handle.net/10454/16916.
Full textAbstract:
YesThis paper presents empirical results of an innovative beam scanning leaky-wave antenna (LWA) which enables scanning over a wide angle from -35o to +34.5o between 57 GHz and 62 GHz, with broadside radiation centered at 60 GHz. The proposed LWA design is based on composite right/left-handed transmission-line (CRLH-TL) concept. The single layer antenna structure includes a matrix of 3×9 square slots that is printed on top of the dielectric substrate; and printed on the bottom ground-plane are Π and Tshaped slots that enhance the impedance bandwidth and radiation properties of the antenna. The proposed antenna structure exhibits metamaterial property. The slot matrix provides beam scanning as a function of frequency. Physical and electrical size of the antenna is 18.7×6×1.6 mm3 and 3.43×1.1×0.29, respectively; where is free space wavelength at 55 GHz. The antenna has a measured impedance bandwidth of 10 GHz (55 GHz to 65 GHz) or fractional bandwidth of 16.7%. Its optimum gain and efficiency are 7.8 dBi and 84.2% at 62 GHz.
Partially supported by innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET- 722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.
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Huang, Chien-Rung, and 黃建榮. "Compact leaky-wave antenna and dual-band circularly polarized slotted monopole antenna." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91288063850864701112.
Full textAbstract:
碩士國立交通大學
電信工程研究所
100
This thesis consists of two parts：1. Using split ring resonators to suppress the side-lobe level of the tapered compact leaky wave antenna. And 2. Using the structures of slots to excite dual-band circularly polarization in monopole antenna. In the first part, we demonstrate two types of suppressing the reflection wave of the leaky wave antenna. The first structure is to put the split ring resonators at the open end of the leaky wave antenna, and the split ring resonators can generate stop-band to suppress the side-lobe level efficiently. The second structure is to etch the split ring resonators in the ground plane, and the reflected wave will couple to the split ring resonators and be trapped. Thus it can be seen that we can use split ring resonators not only to suppress the side-lobe but also to reduce the length of the leaky wave antenna. In the second part, a dual-band circularly polarized monopole antenna using structures of slots will be introduced. The main structure of the monopole antenna is a circular strip and we add a circular patch at the end of the strip. In the ground plane, we etch a L-shaped slot, and this slot play an important role of exciting the circular polarization not only at the lower band but also at the upper band. The most important is that we can choose the different length of the L-shaped slot to operate on the frequency band what we want. On the other hand, we also add two notches at the antenna, and these two notches can adjust the operating frequency band of circular polarization at the upper band. From the above, we can use these simple structures to get circular polarizations.
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Lin, Hung-I., and 林紘毅. "Circularly Polarized Planar Periodic Leaky Wave Antenna and Rotman Lens Array Antenna." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/72452348406405799420.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
100
In this thesis, the proposed periodic leaky wave antenna, which has a simple planar geometry, provides a circularly polarized beam steerable via frequency scanning. The antenna comprises serially connected phase inverters made of parallel strip line. Radiations emit from geometric discontinuities in phase inverter structures and hence form a leaky wave antenna. From simulation and verification results, broad scanning beam coverage is observed with good circular polarization performance. In the second part, an electronically reconfigurable beam switching array antenna applicable to MIMO technology in the 2.4 GHz band is proposed in this work. The array antenna contains a Rotman lens and four element antennas. The Rotman lens, which is a true time delay device, allows simultaneous operation of multiple beams. From the results, the simple beam switching mechanism implemented with the Rotman lens suits well to the MIMO transceiver need.
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Lin, Yu-Chieh, and 林育杰. "Broadband tapered half-width microstrip leaky-wave antenna array." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/10956256395487485901.
Full textAbstract:
碩士國立交通大學
電信工程研究所
103
In this thesis, we used the broadband tapered half-width microstrip leaky-wave antenna as the unit element to design a four-element antenna array. The half-width structure is used to simplify the conventional feeding structure. In the half-width structure, the perfect electric conductor (PEC) wall is realized by via holes connecting the two metallic layers on substrate. The advantages of this structure are : (I) simple feeding structure fed by microstrip line; (II) pure mode excitation and no need to suppress mode; (III) reduced size as compared to the full-width structure; and (IV) less coupling between array element. Based on the characteristics of the first higher order leaky-mode for the microstrip antenna, this thesis proposed a scheme for the empirical design of broadband tapered half-width microstrip leaky-wave antenna array. The measured bandwidth of the antenna has a return loss less than -10 dB from 14 GHz to 30 GHz, yielding a relative bandwidth of 2.3 : 1. In this thesis, we also proposed a novel design scheme for the empirical design of broadband tapered half-width microstrip leaky-wave antenna array to improve the radiation patterns in higher frequency. The measured bandwidth of the antenna has a return loss less than -10 dB from 14 GHz to 30 GHz(relative bandwidth of 2.3 : 1), and the main beam bifurcation in the previous design was alleviated.
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Pu, Ta-Chun, and 浦大鈞. "A Planar Shaped-Beam Antenna using Leaky-Wave Characteristics." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/33171150912397895774.
Full textAbstract:
博士國立交通大學
電信工程系所
95
In this thesis, the shaped-beam antennas were investigated systematically using theoretical analysis and experimental measurement. The basic structure of the shaped-beam antenna contains a line source, taken as an excitation source, embedded in an air substrate sandwiched between a metal reflector and a grating made of metallic or dielectric material. Due to the contribution of leaky wave caused by the grating and direct wave radiating directly from the line source, such a shaped-beam antenna can radiate uniform electromagnetic field pattern over a rectangular plane in front of the antenna. In addition to the fabrication and measurement for the radiation characteristics of this antenna, the rigorous mode-matching method was employed to study the electromagnetic fields within the structure and the radiation far-field pattern, as well. Furthermore, the sensitivity analysis for the parameters including the geometric structure and electrical property of the dielectric material was taken into account to understand the tolerance of this antenna during fabrication. Since this antenna can radiate uniform coverage over a rectangle footprint, it can be a good candidate for serving as the antenna of a hyper LAN (local area network) access point in millimeter wave applications.
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Tsai, Chu-Yung, and 蔡志陽. "High Directivity Double-Layer Leaky-wave Microstrip Array Antenna." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/53545946582725993256.
Full textAbstract:
碩士義守大學
電子工程學系碩士班
95
Among all kinds of antennas, high-directivity and wide-band leaky-wave microstrip antennas have earned much attention. In addition, their co-planar structures are easy to integrate in wireless communication system and double-layer structure can provide more design freedom. However, the low directivity from the double-layer leaky-wave microstrip antenna cross-section limits its applications, therefore this thesis uses a double-layer as foundation to design a high-directivity leaky-wave array. First, this thesis establishes the concept of a leaky-wave antenna, the way to observe radiation, as well as how to use cavity model to deal with a leaky-wave structure by using a simple single-layer structure. As observed, simulation data and semi-empirical approximation method compensate the disadvantages from the theoretical results. While applying to the double-layer antenna, the theoretical and simulated data after modification effectively obtain antenna characteristics, such as electric field distribution, electromagnetic wave propagation behavior and antenna radiation. As the connection of array elements with the demand of impedance matching, feeding simplification and high directivity, this thesis uses a novel arraying technique to design a microstrip array. The employment of double-layer structure has not only increased design freedom but also made the whole array easy to combine with other communication components. Moreover, the arraying technique simplifies feeding structure and decreases the coupling due to the use of multiple feedings, thus the overall gain of arrays can be increased. Meanwhile, this technique applies an extra half-wavelength microstrip structure, the shorting-end microstrip structure to eliminate magnetic currents, and asymmetrical microstrip structure as an input element, thus radiation or impedance mismatching are improved. In addition, the physical-intuitive cavity model establishes the concept of element connection directly; it simplifies the analysis procedure and also effectively obtains array characteristics. The whole idea is straightforward for the understanding of arrays. The technique introduced here is originally for leaky-wave microstrip antennas with uniform width, but it can be applied to those structures with various geometry.
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Liu, Shih-Jeng, and 劉仕正. "The Study of X-Band Conductor-Backed Coplanar Strip-line Feeding Leaky-Wave Antenna and Ku-Band Asymmetric Feeding Leaky-Wave Antenna Applications." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/08906380901884707638.
Full textAbstract:
碩士國立交通大學
電信工程系
87
In this report, we present a X-band Conductor-Backed Coplanar Waveguide-to Conductor-Backed Coplanar Strip-line HEMT Oscillator Frequency Scanning Leaky Wave Antenna (LWA), an X-band Quasi-Omni-Directional scanning Leaky Wave Antenna, and a Ku-band Dual-Beam array of LWAs. In the first part, the active source sweeps from 9.32 GHz to 9.67 GHz and the main beam scan 11 degrees in the H-plane. The LWA with a CBCPW-to-CBCPS feeding structure excites the first higher mode easily than the CPW-to-CPS feeding structure and retains the advantages of the CPW and the CPS. In the second topic, the CPW-Center fed LWA generates four beams in the H-plane so that forms a scanning range of about 220 degrees. Antenna from 8.7 to 11.3 GHz makes each beam scan 60 degrees in the H-plane. The CPW-Center fed LWA generates four beams in the H-plane so that forms a scanning range of about 220 degrees. In the 3rd part, a Ku-band Dualbeam array of LWA is demonstrated at 15.5 GHz. The measured antenna results indicate that the 2-element and 4-element array has a power gain of 2.56 dB and 5.06 dB are higher than the single element antenna, respectively. The E-plane radiation pattern is improved by increasing the number of array also. Changing the phase of the excitation current, we successfully eliminated the side lobe in the broadside of antenna. The main beam shifts 5 degrees when the number of array increased from 1 elements to 4 elements.
40
Chiu, Wen-Tou, and 邱文斗. "Design of Low Side Lobe Level Leaky Wave Antenna Array." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/64701332306837531596.
Full textAbstract:
碩士國立交通大學
電機學院碩士在職專班電信組
98
In this paper, We propose a compact leaky-wave Antenna array to reduce side lobe level. Since the travelling wave propagating on the antenna will leak out the energy to the free space. But due to the discontinuity at the end of the antenna that will cause the reflected wave and propagate opposite direction. Then radiate unwanted side lobe. We reuse the reflected power due to the reflected power from the end of the microstrip line can reduce the side lobe level. The antenna array consist of 3 elements, each one has 1? long. We guided the remained reflected power and split the power equally with the same phase difference into 2 paths then inject into each antenna elements. This antenna is fabricated on FR-4 PCB and operating at 4.4GHz. And the measurement results shows gain +8.5dBi, main beam angle is about 30?a, beam width is about 40?a and side lobe level is -13dB. This design can reduce side lobe level effectively which may reduce the interference and utilize the array structure to improve the directivity. It is suitable for vehicles avoidance collision system, point-to-point radio communication and millimeter-wave applications.
41
Wang, Shih-Hung, and 王世宏. "Leaky-wave Antenna Array Approach for Automotive Collision-Avoidance Radar." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/14093905069506002344.
Full textAbstract:
碩士國立交通大學
電信工程系
91
In this thesis, we propose two kinds of antenna array to apply to automotive collision-avoidance radar at 24 GHz, and provide the illustration of the basic system requirements for automotive collision-avoidance radar. The foundations of all proposed antennas in this thesis are microstrip leaky-wave antennas with low profile, low cost, high directivity, and high radiation efficiency. The structure of all proposed antennas in this thesis are microstrip leaky-wave antenna with aperture-coupled feed, operating in first higher order mode. We can obtain the radiation patterns conformed with the system requirements for automotive collision-avoidance radar by use of wave-composed and multi-section radiation. Besides, the waveguide model is used to calculate the radiation pattern. The first kind of antennas are fed from the center of microstrip line produce dual-beam, composing with 1×8 leaky-wave array, and we can obtain three beam pattern. Besides, we can change the structure of microstrip line to obtain antennas with different radiation pattern﹔The second is dual-beam with fixed beam and broad-beamwidth by use of multi-section microstrip line, whose included angle between the dual-beam is about 90°, and peak-gain is about 13.2 dBi at 24 GHz.
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Chen, Jian-Hong, and 陳建宏. "Applications of Microstrip Leaky-Wave Antenna Array in X-band." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/82816321798409970449.
Full textAbstract:
碩士國立交通大學
電信工程系
87
Three applications on microstrip leaky-wave antenna array are proposed in this thesis. By forming a pair of microstrip leaky-wave antennas into a vee-shaped array, a planar-type vee antenna with a pencil-beam is realized in chapter 2 of this thesis. The waveguide model is used to calculate the radiation pattern, and is in agreement with the measured pattern. Two wideband broadside CP antenna arrays are discussed in chapter 3. The first is a CP cross antenna array with single feed. The second is a dual CP antenna array with two feeds. A linear array of microstrip leaky-wave antennas with the property of retrodirectivity is discussed in chapter 4. By the principle of Van Atta antenna array and the tilt beams of leaky-wave antennas, it is both retrodirective in E plane and H plane.
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Hu, Cheng-Chi, and 胡政吉. "The Study of the Active Microstrip Leaky-Wave Antenna Arrays." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/74867868075462980935.
Full textAbstract:
博士國立交通大學
電信工程系
87
This thesis demonstrated an active phased array design for electronic two-dimensional beam scanning using a phase-shifterless linear one-dimensional active leaky-wave antenna array. The varactor-tuned voltage controlled oscillators (VCOs) and coupling network are implemented in this array. Three coupling networks are designed and compared for optimum coupling strength between each VCO elements. Here, we demonstrated an asymmetric microstrip line fed linear active phased antenna array with two-dimensional beam-scanning capability without using phase shifters. The coupling transmission line enhances the mutual synchronization of the active antenna array. The controlling of the free-running frequency is achieved by tuning the varactor''s DC bias, which also gives an additional advantage of fine tuning the scanning angle of the array. The measured pattern of a 4×1 active leaky-wave antenna array shows that the main beam can be continuously scanned from 68°to 40°in elevation as the frequency varied from 8.24 GHz to 9.15 GHz. This is equivalent to over 10% electronic tuning bandwidth. By tuning the free running frequencies of the end elements, the main beam can be continuously scanned from -26°to +10°from broadside with azimuth symmetry in a conical scan manner. Beside, we also used the other feeding structures (for examples, the CPW-CPS, CPW-slot line and aperture feedings) in the active microstrip leaky-wave antenna arrays for more applications. In this thesis, a new spatially power combining array using microstrip antenna as radiating elements are also be developed, which possesses two switching radiation modes. It is shown that a simple lumped element coupled oscillator theory, with compared experimental results, can predict the frequency and phase behavior of a network of two-element coupled oscillators. A two-element dual-beam back-to-back CPW-slotline fed active microstrip leaky-wave antenna array was demonstrated to verify the mode-switching phenomena. The CPW-slot has been shown to be a correct feeding structure for the excitation of the leaky mode. The dual-beam is achieved in the H-plane radiation patterns. Two-way switching phenomenon of the radiation patterns in the quasi-E-plane was achieved by controlling the dc bias of one of the Gunn devices. The initial results show a good potential of using this circuit for low cost transmitters, spatial power combiners and collision warning radar applications. Furthermore, two-terminal devices, for example, the Gunn diodes have the advantages over three terminal devices such as higher cutoff frequency, simpler bias circuit, and they are suitable for monolithic millimeter-wave integration circuit.
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Zeng, Guan-Ling, and 曾冠菱. "Dual-Polarized Slotted Conductor-Backed Coplanar Waveguide Leaky-Wave Antenna." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/85695786639881797377.
Full textAbstract:
碩士國立交通大學
電信工程研究所
104
Conductor-backed coplanar waveguide (CBCPW) propagates electromagnetic waves via dominant modes (coplanar waveguide mode), and excites leaky wave which propagates toward both sides despite the value of the frequency. In general, there are two applications based on this structure: first is to use such property to design the antenna; the other is to suppress the leaky wave through some methods in order to decrease the unnecessary couplings and crosstalk. Implementing the full wave analysis (Spectral Domain Approach) on the CBCPW structure, we can discover that the leaky wave propagates along a particular angle relative to the main CPW line, causing the wave to propagate as if in a parallel plate waveguide (PPW). Therefore, we can etch rectangular slots along the ground planes with the angle we have acquired. If the length of the slot is significantly longer than the width and approximately equals to half the guided wavelength, the slots fed by CBCPW will radiate power efficiently .We can thus obtain a centralized broadside radiation pattern and a dual-polarization antenna.
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陳一宇. "Microelectromechanical-Based Novel Antenna Design and 2-D Active Scanning Leaky-Wave Antenna Array." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/63174883871228039884.
Full textAbstract:
博士國立交通大學
電信工程系所
94
This thesis consists of two parts: Microelectromechanical technology based novel antenna design and the study of suppression of the reflected wave and beam-scanning features of the leaky-wave antenna array. In the first part, the design, fabrication and measurement of two types of micromachined antennas were presented. One is a flexible monopole antenna which was fabricated on parylene substrate, and the other is a 3D monopole antenna which was fabricated on both sides of a Pyrex 7740 glass wafer with through-hole connections. Flexible dual-band (2.4/5.2 GHz) monopole antennas were designed with meander-shaped metal tracks, because this can efficiently reduce the physical dimensions of the overall antenna size and maintaining the required electrical path-length. Due to parylene’s excellent physical, mechanical and chemical properties such as low dielectric constant, high resistivity, and inertness to chemicals, it can serve as a substrate for an antenna in our study. The advantages of these antennas are their small size, light weight, low cost, dual-band characteristics, broad bandwidth, and flexible. A compact 3D MEMS monopole antenna was also demonstrated. In order to reduce the size, the meandered monopole antenna was fabricated on both sides of a Pyrex 7740 glass wafer, and the metal lines on both sides were connected through via-holes. Measured performances of the fabricated 3-D antenna are in good agreement to the designed values in terms of operating frequency at 2.45 GHz and with a bandwidth of 190 MHz. This simple fabricated size low cost antenna is suitable for communication applications. In the second part of the dissertation, a two-directional linear scanning array was demonstrated by integrating a short leaky-wave antenna (LWA) with aperture-coupled patch antenna arrays on the backside. This active scanning antenna has many special functions known by experimental results. This architecture proposes a technique not only having the advantage of suppressing the back-lobe due to the reflected wave of the short LWA but also producing two separate linearly scanned beams in a different region of space. By tuning the backside individual phase shifter, the phase of this coupled signal to each antenna element can electronically control the patch antenna main beam on the backside. And simultaneously by changing the operating frequency, the main beam of the short LWA can scan on the front side. As a result, the two linear beam-scanning radiation patterns of individual direction can be created independently, which includes a narrow beam in the elevation plane at the front side and a broadside beam in the cross plane on the backside. This designed array scanning capability is suitable for military application, air traffic control, collision avoidance system, or radiolocation, etc. Thus, there is great potential for application in the future.
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Lee, Tsung-Han, and 李宗翰. "The Analysis of Antenna Parameters for the Tapered Double-Layer Leaky-wave Microstrip Antenna." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/97139357247250154911.
Full textAbstract:
碩士義守大學
電子工程學系
91
As the dramatically increasing of broadband application in wireless systems, the demands of broadband antenna thus increase as well. Among those broadband antennas, leaky-wave microstrip antennas have earned great attention because of their light weight, compactness and ease to fabricate. Besides these advantages, electromagnetic waves in this kind of antenna radiating while propagating can provide broader bandwidth. In addition, the employing of double-layer structure offers leaky-wave microstrip antenna more various parameters to adjust in order to satisfy various demands. Among these parameters, when the width of the strip on the substrate varies from uniform to tapered geometry, the cut-off frequency of leaky-wave microstrip antenna also increases as strip width reduces. For this reason, electromagnetic wave that original cannot radiate under uniform structure can also propagate and contribute radiation. The phenomenon of bandwidth enhancement was confirmed by experiments, but theoretical analysis is not sufficient yet. However, to perform the analysis requires phase and attenuation constants, which could be a tough job due to the complexity of the tapered structure. Hence, this dissertation suggests that the stepped function is used to approximate the original tapered structure and solve for complex propagation constant of each antenna section. The approach is verified by bandwidth and reduces computational efforts. Moreover, the electric filed and current distribution of this antenna can be also obtained for future analysis. The antenna parameters of the tapered double-layer leaky-wave microstrip antennas can be used to compute other antenna parameters such as far-field radiation and input impedance, therefore antenna characteristics can be controlled effectively for future applications.
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Yang, Shang-Te. "Design and application of microstrip leaky wave antennas for radar sensing." Thesis, 2014. http://hdl.handle.net/2152/26933.
Full textAbstract:
This dissertation investigates the application of the frequency-scanned beam of a microstrip leaky wave antenna (LWA) to track humans in the two-dimensional (2-D) range-azimuth plane. The history, operating principles and frequency-scanned properties of a microstrip LWA are first reviewed. The basic concept of using a microstrip LWA to track humans is verified by designing, building and testing a broadband microstrip LWA, developing the necessary processing algorithm, and collecting data using a vector network analyzer. A number of topics are then investigated to further advance the concept. First, the idea of combining the frequency-scanned antenna with a short-pulse ultra-wideband (UWB) radar is developed to realize a portable, real-time system for human tracking. The radar concept and the components of the system are discussed in detail. Line-of-sight and through-wall measurements of a human subject are carried out to demonstrate the performance. Second, a new LWA structure is proposed to achieve a narrower azimuth beam, which requires both a small leaky-wave attenuation constant and a long aperture. The transverse resonance method (TRM) is applied to analyze the proposed structure and the results are verified with measurements of a built prototype. Third, a new signal processing technique, compressive sensing, is applied to further improve the resolution in both the azimuth and down range dimensions. The technique is tested with simulation and measurement data and is shown to produce sharper target responses in both the down range and azimuth dimensions. Lastly, the radar cross-section (RCS) of a microstrip LWA is studied. The antenna mode scattering and structural mode scattering are modeled separately. A ray picture is provided to explain the observed time-domain features using the group delay of the leaky wave.text
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shih, han-rong, and 施漢嶸. "Suppression of Reflected Wave of a short Microstrip Leaky-Wave Antenna By Utilizing A Microstrip-Fed Slot Antenna." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/35153849634450751795.
Full textAbstract:
碩士國立交通大學
電信工程系
89
In this thesis, the suppression of the reflected wave of microstrip leaky wave antenna is studied. A microstrip-fed slot antenna is integrated on the backside of the microstrip leaky wave antenna (MLWA) in order to suppress the reflected wave and leak the residual power. Three types of microstrip-fed slot antenna have been designed, which are: one wavelength slot antenna, microstrip-fed first higher-order mode slot antenna and microstrip-fed folded slot antenna. The above antennas are designed at X-band. The two different antenna modes are excited at the top and bottom of a microwave substrate. The microstrip-folded slot antenna array is designed at the backside of a microwave substrate. At the top plane of a microwave substrate, the leaky wave antenna is frequency-dependent scanning and at the backside the microstrip-folded slot antenna array is scanning by different phase feeding. This circuit has the ability of the vertical and horizontal scanning and is constructed in a single-layer microwave substrate.
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Kuo, Hung-De, and 郭宏德. "Tapered Microstrip Leaky-Wave Antenna with Low Sidelobes for Broadband Operation." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/38m8j2.
Full textAbstract:
碩士國立交通大學
電信工程系所
95
Generally, leaky wave antennas have the advantages: high gain, high radiation efficiency, low cost. In this thesis, we study the first higher order mode broadband microstrip leaky-wave antennas. We will implement the first higher order mode leaky wave antenna by the broadband balun. The inverted balanced microstip line structure is developed from the balanced microstrip line. The position of the positive strip on the upper substrate side is exchanged with that of the negative strip on the lower substrate side by the method proposed in this thesis.United with the balanced microstrip line, this inverted balanced microstrip line can be used to form into a pair of broadband baluns. Using this broadband balun can realize a broadband leaky-wave antenna. Based on the characteristics of the first higher order leaky-mode for the microstrip antenna, this thesis proposes a scheme for the empirical design of broadband tapered microstrip leaky-wave antenna. The measured bandwidth of the tapered microstrip leaky-wave antenna has a from 10GHz to 40GHz, yielding a relative bandwidth of 4:1. Finally, this thesis proposes a novel scheme for the empirical design of lower sidelobe broadband tapered microstrip leaky-wave antenna.
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Shih, Ying-Chou, and 施盈舟. "The Study of Asymmetric Feeding X-Band Leaky-wave Antenna Applications." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/67796047901113313360.
Full textAbstract:
碩士國立交通大學
電信工程系
87
In recent years, due to the increasing of wireless communication markets and automatic applications, the needs of compact transmitters, active arrays, spatial power combiners and radar sensors will increase steadily. The leaky-wave antenna is an area of recent research. Because of its frequency scanning ability, it could be used to provide antenna beam steering instead of conventional phase scanning techniques, which require complex associated drivers. In this report, we used the asymmetric leaky-wave antennas to produce two kinds of applications. The first one is Active Integrated Feedback-Amplifier Leaky-wave Antenna Design with Suppressed Back Lobe, and the other is Dual-Beam Leaky-wave Antenna with Control circuit. The first one successfully suppressed the back lobe to be lower than main beam about 15dB at 8.23GHz with EIRP 19.5 dBm and the leaky-wave antenna length is only 9cm. The second one using SPDT as control circuit can change the radiation pattern as one or dual beam receiving or transmitting antenna. Besides, by changing the frequency, dual beam mode can scan from 36°to 64°as the operating frequency from 10.6 GHz to 9.2 GHz ( total scanning angle about 64°) and one beam mode can scan about 40°as the operating frequency from 9.3GHz to 10.4GHz ( each left and right main beam covers 20°).