Dissertations / Theses on the topic 'Waveguide polarizer'

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
Includes bibliographical references (leaves 70-71).
by Jonathan J. Klaren.
M.S.

In the recent astrophysical experiments i.e. QUIET, QUIJOTE, STRIP-LSPE, arrays of polarimeters are used in order to measure the linearly polarized component of the Cosmic Microwave Background Radiation (CMBR). Since the signal of interest is very faint, the sensitivity of the scientific instrumentation should be very high. This goal can be achieved by accommodating a large number of high-performance polarimeters in the focal plane of the antenna. In this perspective, a novel layout of Ortho-Mode-Transducer (OMT) and polarizer, which are key passive waveguide elements of dual-circular polarization polarimeters, have been designed. The polarizer is based on a Dual-Fold-Stub (DFS) design having 20% bandwidth centered at 94.5GHz, whereas the broadband OMT exploits a turnstile junction with 30% bandwidth centered at 94 GHz. The components are realized using the multi-layer technology, where each metallic plate is manufactured by wire spark erosion technique. Using this design methodology, several identical devices can be manufactured in a single machining process. The exploitation of multi-layer technology in conjunction with wire spark erosion technique provides high level of manufacturing repeatability and accuracy along with low cost, making this solution well suitable for the realization of polarimetric arrays consisting of tens/hundreds of chains. The propriety SEM (Spectral Element Method) tool of IEIIT-CNR and commercial EM (Electromagnetic) tools (CST-MWS & HFSS) have been exploited in an effective manner to achieve the required performances. In order to integrate MATLAB with EM tools, COM EM Automation Tool (COM-EM-AT) has been developed and exploited in various manner to attain the final design. The simulation acceleration through distributed computing have also been employed efficiently for tolerance analysis using the SEM tool.

The purpose of the thesis is to design transmitting antenna based on septum polarizer solution for indoor measurement range. The antenna is considered for both senses of circular polarization. The design is divided into three main sections. First section is devoted to analysis and selection of a suitable waveguide. Ridge waveguide as a crucial part of a septum polarizer is mentioned in this section. Second part is the most critical; here the septum polarizer is analyzed and based on simple procedure also designed. Two suitable horn apertures are then developed as a part of the third section. Individual transmitting antenna parts are assembled together into one model and simulated with excellent results for axial ratio, cross-polarization discrimination, return loss and isolation between ports.

The work addresses the unusual proposal feed for parabolic antenna with circular polariza-tion signal. This is a modified waveguide feed, waveguide polarizer with a septum. Contemporary RHCP and LHCP wave occurs in several applications of microwave commu-nication and measurement system. From this point of view the septum polarizer can be useful. The septum polarizer is a four-port waveguide device. The square waveguide at one end con-stitutes two ports because it can support two orthogonal modes. A stepped septum divides the square waveguide into two standard rectangular waveguides sharing a common broad-wall. The size of the septum as well as two versions of the waveguides excitation were analyzed and are described in this paper. Ansoft HFSS is software for design and simulation of feed. This software can visualize not only the specified model feed, but also the course of electromagnetic field in feed and over time.

An X band dual polarized slotted waveguide antenna array is designed with very high polarization purity for both horizontal and vertical polarizations. Horizontally polarized radiators are designed using a novel non-inclined edge wall slots whereas the vertically polarized slots are implemented using broad wall slots opened on baffled single ridge rectangular waveguides. Electromagnetic model based on an infinite array unit cell approach is introduced to characterize the slots used in the array. 20 by 10 element planar array of these slots is manufactured and radiation fields are measured. The measurement results of this array are in very good accordance with the simulation results. The dual polarized antenna possesses a low sidelobe level of -35 dB and is able to scan a sector of ±
35 degrees in elevation. It also has a usable bandwidth of 600 MHz.

This thesis discusses Slot antennas that are based in gap waveguide technology, which allows them to work with high frequency signals. It contains theoretical findings about antennas and waveguides, which are later used in the design. The practical section of this thesis concentrates on designing a specific gap waveguide for 10 and 24 GHz frequencies, starting with modeling and parameter optimalization. This gap waveguide is then used as a base for slot antenna design. The final antenna is designed for frequency of 10 GHz, for both linear and right-handed circular polarizations. With right-handed circular polarization, the achieved band was approximately 1.41 GHz, while the gain was 7,6 dB.

[ES] Esta tesis aborda temas de especial interés en el diseño de antenas en la banda de milimétricas. Hui en dia, implementar components passius per a operar en la banda de mil·limètriques i assegurar el contacte i l'alineament metàl·lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guies d'ones metàl·liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl·lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnología Gap Waveguide (GW) resulta adecuada ya que no requiere de contactos metálicos. En los últimos años han surgido las agrupaciones de antenas basadas en la tecnología Gap Waveguide y son un candidato prometedor para satisfacer algunas de las necesidades mencionadas. La tecnología GW ha demostrado ser atractiva para dispositivos de milimétricas porque permite redes de distribución completamente metálicas de una manera más simple que las guías de onda convencionales. Por tanto, estas redes tienen muy bajas pérdidas pero además son simples de fabricar. Esto es posible gracias a la capacidad de las GW de confinar de forma segura la propagación de ondas electromagnéticas por medio de una estructura que no requiere de contacto. Durante la última década, se han hecho avances importantes en la tecnología GW y en la literatura se pueden encontrar un buen número de antenas basadas en GW. Esta tesis va un paso más allá en la contribución de este tipo de antenas. Aquí, no solo se presentan antenas con polarización lineal, como suelen ser las desarrolladas hasta ahora, sino también con polarización dual, circular y duales en banda. Estas aportaciones son especialmente atractivas dentro del campo de las comunicaciones por satélite en movimiento (SATCOM on-the-move). Además, se han explorado nuevas redes de distribución que permiten antenas planas más compactas, más ligeras.
[CAT] Esta tesi aborda temes d'especial interés en el disseny d'antenes en la banda de mil.limètriques. Hui en dia, implementar components passius per a operar en longituds d'onda tan xicotetes (de l'orde de mil.límetres) i assegurar el contacte i l'alineament metàl-lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guia d'ones metàl.liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl.lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnologia Gap Waveguide (GW) resulta adequada ja que no requerix de contactes metàl.lics. En els últims anys han sorgit les agrupacions d'antena basades en la tecnologia Gap Waveguide i són un candidat prometedor per a satisfer algunes de les necessitats mencionades. La tecnologia GW ha demostrat ser atractiva per a dispositius de banda d'ones mil-limètriques perquè permet xarxes de distribució completament metàl-liques d'una manera més simple que les guies d'onda convencionals. Per tant estes xarxes tenen baixes pèrdues peró, a més, són simples de fabricar. Açò és possible gràcies a la capacitat de les GW de confinar de forma segura la propagació d'ones electromagnètiques per mitjà d'una estructura que no requerix de contacte. Durant l'última dècada, s'han fet avanços importants en la tecnologia GW i en la literatura es poden trobar un bon nombre d'antenes basades en GW. Esta tesi va un pas més enllà en la contribució d'este tipus d'antenes. Ací, no sols es presenten antenes amb polarització lineal com solen ser les desenrotllades fins ara, sinó també antenes amb polarització dual, circular i inclús antenes duals en banda. Estes aportacions són especialment atractives dins del camp de les comunicacions per satèl.lit en moviment (SATCOM on-the-move). A més també s'han explorat noves xarxes de distribució que permeten obtindre antenes planes més compactes, més lleugeres.
[EN] This thesis deals with topics of special interest regarding the design of antennas at the mm-wave band. Today, implementing passive components that operate in the mm-wave band and to ensure the appropriate metallic contact is challenging. Commonly, conventional planar transmission lines and hollow metallic waveguides are the usual solutions but they present high losses or they do not ensure a good metallic contact. So, new concepts must be explored. Gap Waveguides (GWs), result suitably since they do not require metallic contact for shielding. Antenna arrays in Gap Waveguide Technology (GW) emerges as one promising candidate to naturally meet some of the mentioned needs. GW technology has demonstrated to be effective for mm-wave band devices because it enables full-metal distribution networks in a much simpler way than conventional waveguides. Very low distribution losses can be achieved preserving at the same time the assembly simplicity of multilayer microstrip feeding networks. This unique feature is a consequence of gap waveguides ability to safely confine the electromagnetic wave propagation through a contactless structure. During the last decade, there have been important advances in GW technology and a good number of gap waveguide-based arrays can be found in the literature. This thesis goes a step further in the contribution to mm-wave gap waveguide antennas. Here, antennas with linear polarization as well as circular or dual polarization are proposed. Dual band antennas has also been explored. These contributions have been carried out with a focus on satellite communications on-the-move. In addition, new distribution networks have also been explored to obtain more compact, low-profile and lighter antennas.
Ferrando Rocher, M. (2018). Gap Waveguide Array Antennas and Corporate-Feed Networks for mm-Wave band Applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115933
TESIS

Ce travail est consacré à l’étude de la génération de deuxième harmonique (SHG) dans des guides d’ondes de Nitrure d’éléments III. Un des buts principaux de ce travail, était d’identifier les origines des pertes à la propagation dans les guides d’ondes GaN et de fortement les réduire dans des guides présentant des possibilités d’accord de phase, pour améliorer l’efficacité de la SHG. Nous avons fait un progrès très important dans cette direction et avons fabriqué des guides d’ondes plans de GaN épitaxiés sur des substrats de saphir avec des pertes à la propagation inférieure à 1dB/cm dans le visible. Dans ces guides d’ondes à faibles pertes, il a été possible d’obtenir un processus de SHG efficace en utilisant l’accord de phase modal. Nous avons obtenu 2% de conversion entre une pompe dans le proche infrarouge et un harmonique dans le visible, ce qui correspond à une efficacité de conversion normalisée de 0,15%W-1cm-2. Les pertes à la propagation et l’efficacité de conversion obtenues sont les meilleurs résultats rapportés jusqu'ici pour des guides d’ondes plan en GaN. De plus, nous avons étudié des guides d’ondes de Nitrure d’éléments III épitaxiés sur des substrats de Si, dont la fabrication demande de relever plusieurs défis, mais qui ouvrent des possibilités intéressantes. La première est la possibilité de graver sélectivement les nitrures ou le Si, ce que nous avons utilisé pour développer une plate-forme permettant la fabrication d’objets suspendus comme des micro-disques, des guides d’ondes et des micro-disques couplés à un guide d’ondes. Cette plate-forme a permis la première démonstration de SHG doublement résonante en utilisant un accord de phase modal entre des modes de galerie du micro-disque. Bien que toutes les expériences que nous avons exécutées aient été faites dans une région spectrale limitée, l’étude numérique présentée dans ce manuscrit démontre la grande adaptabilité de cette plate-forme basée sur la possibilité de faire varier la composition des guides d’ondes AlGaN de GaN pur à AlN pur. La deuxième possibilité liée à l’épitaxie de nitrures d’éléments III sur Si, est qu'en la combinant avec des techniques de report, on peut jouer avec des guides nitrures d’éléments III sur SiO2. Nos résultats numériques révèlent le potentiel complet des guides d’ondes d’AlGaN en démontrant qu’en utilisant différentes combinaisons de mode et en jouant sur la composition et la géométrie des guides d’ondes, il est possible d’obtenir un signal de deuxième harmonique dans l’ultra-violet, le visible ou le proche-infrarouges. Ces résultats montrent aussi, que pour améliorer encore l’efficacité de la SHG, on doit fabriquer des guides d’ondes canaux présentant un isolement optique parfait du substrat de Si et une inversion de polarité précisément placée dans le cœur du guide d’ondes. Dans une telle structure on pourrait profiter simultanément du confinement de la puissance, de l’accord de phase modal et d’un recouvrement optimisé des modes en interaction. Dans ce cas, nos calculs montrent que l’efficacité de conversion pourrait atteindre 100%W-1cm-2. Au cours de ce travail nous avons pu tester des guides canaux et des guides présentant une inversion de polarité dans le cœur. La qualité des flancs des guides canaux s’est avérée être tout à fait encourageante, mais leur performance non linéaire sont restées très limitées, principalement à cause de fortes pertes à la propagation dues au couplage avec le substrat absorbant et à la forte rugosité de surface des couches inversées. Les structures utilisant les techniques de report, n'ont pu être testées car elles ont cassé en cour de fabrication. L'obtention de guides optimisés exige de progresser encore pour réaliser des couches de confinement optique plus épaisses et/ou d’adapter la technique de report à ces matériaux
This work is dedicated to the study of the second harmonic generation (SHG) in III-Nitride waveguides. One of the main goals of this work, was to identify the origins of the propagation losses in GaN waveguides, and to strongly reduce them in waveguides presenting some phase matching possibilities, in order to improve the SHG efficiency. We have made a very important progress in this direction, and fabricated by hetero-epitaxy GaN planar waveguides on sapphire substrates with propagation losses below 1dB/cm in the visible spectral region. These low-loss waveguides were used for the demonstration of an efficient second harmonic generation process using modal phase matching. We obtained 2% of power conversion from the near-infrared to the visible spectral regions with a normalized efficiency of 0.15%W-1cm-2. The obtained propagation losses and conversion efficiency are the best-reported results so far for GaN planar waveguides. In addition, we have studied epitaxial III-nitride waveguides on Si substrates, which are very challenging to fabricate, but opens new interesting opportunities. The first one is the possibility to etch selectively the nitrides or the Si. The selective chemical etching was used to develop a platform allowing the fabrication of suspended objects such as micro-disks, waveguides and micro-disks coupled to a waveguide. This platform has allowed the first demonstration of doubly resonant SHG using phase matching between the whispering gallery modes of a micro-disk. Although all the experiments we performed were done in a limited spectral region, the numerical study presented in this manuscript demonstrates the large adaptability of this platform based on the possibility of varying the composition of AlGaN waveguides from pure GaN to pure AlN. The second opportunity of epitaxial III-nitrides layers on Si is the possibility to combine them with report technologies to obtain III-nitride waveguides on SiO2. Our numerical results reveal the full potential of AlGaN waveguides by demonstrating that using different mode combinations and playing with waveguides composition and geometry, it is possible to obtain a second harmonic signal in the ultraviolet, the visible or the near-infrared spectral regions. These results also demonstrate, that to further improve the SHG efficiency, one has to fabricate ridge waveguides presenting a perfect optical isolation from the Si substrate and a polarity inversion precisely positioned in the core of the waveguide. In these structures one could benefit simultaneously from the power confinement, the modal phase matching and an optimized overlap of the interacting modes. In this case, we calculate that the conversion efficiencies could be as high as 100%W-1cm-2. Both ridge waveguides and polarity inversion were tested in this work. The quality of the ridges was quite encouraging, but their nonlinear performance remained limited mainly because of the high propagation losses due to the coupling with the absorbing substrate and to the roughness of the surface of the epitaxial inverted layers. The structures fabricated using the report technique, haven’t been tested, as they were broken during their fabrication. Getting fully optimized waveguides requires further progresses in realizing thicker optical buffer layers and/or adapting the report technique to these materials

Práce je zaměřena na výzkum struktur založených na vlnovodu integrovaném do textilu (TIW). Pozornost je věnována elektrické charakterizaci textilních materiálů (textilní substráty, nitě), které jsou využívány při implementaci antén, rekonfigurovatelných a aktivních obvodů integrovaných do textilu. Práce se zabývá návrhem vícevrstvých přechodů mezi mikropáskovým vedením na konvenčním substrátu a vedeními integrovanými do textilu. Dále je prezentován koncept přepínače integrovaného do textilu. Přepínač je řízen vodivými sloupky, které vytvářejí otevřenou či zavřenou stěnu prostřednictvím stejnosměrně ovládaných PIN diod. Na závěr je formulována metodika návrhu kruhově polarizovaných antén integrovaných do textilu, jež jsou určeny pro práci v ISM pásmech až do 24 GHz. Všechny postupy návrhu byly ověřeny simulacemi a měřeními reálných vzorků, které byly vyrobeny sítotiskem stříbrnou polymerovou pastou. Polovodičové komponenty byly k obvodům přilepeny vodivým stříbrným lepidlem. Komponenty vyrobené sítotiskem byly porovnávány s referenčními strukturami, které byly realizovány pomocí samolepicí měděné fólie.

碩士
國立臺灣科技大學
電子工程系
104
In this discourse, two compact microwave components are proposed, which include the compact and broadband CPW-to-RWG transition using the inductance compensated phase shifter and the compact microstrip-fed CWG polarizer using the corner-truncated patch. The characteristics of each of them are described below. In chapter 2, firstly, a CPW-to-RWG transition using the half-wavelength phase shifter is introduced. The transition has a broadband response in which the frequency range of the -15-dB reflection coefficient covers from 8.05 GHz to 12.18 GHz (FBW = 38.8%), almost encompassing the whole X-band (8.2-12.4 GHz). In order to reduce the size of the transition, the inductance-compensated phase shifter is used to replace the half-wavelength phase shifter, resulting in a compact and broadband CPW-to-RWG transition using the inductance-compensated phase shifter. The size of transition is 5.9×10.16×0.8 mm3 and the frequency range, for which the reflection coefficient is smaller than -15 dB, covers from 8.05 GHz to 12.38 GHz, estimating to be 42.04%. In order to verify the simulation results, two CPW-to-RWG transitions using the inductance-compensated phase shifter are back-to-back connected, fabricated, and measured. The measurement and simulation results are in reasonable agreement, which verifies our design. In chapter 3, firstly, a MSL-to-CWG transition using the rectangular patch is introduced. The rectangular patch is placed 2.68 mm (0.043 λg) away from the short-circuited plane of the CWG port, making the transition very compact. Secondly, a MSL-fed CWG polarizer using the corner-truncated patch is proposed. The proposed polarizer has an axial ratio of 0.002 dB and a phase difference of -90.97° at 9.65 GHz. The reflection coefficient is below -20 dB around the center frequency 9.65 GHz. In additional, the proposed polarizer needs no complex manufacturing process on the waveguide. Moreover, since the polarizer is fed by the microstrip line, it would be easy to integrate with other planar circuits. In order to verify the simulation results, the CWG port of the MSL-fed CWG polarizer using the corner-truncated patch is opened, simulated and measured. The simulation and measurement results are in good agreement.

碩士
國立中山大學
光電工程學系研究所
103
Silicon on insulator (SOI) structures is proven to be a very promising technology for developing high-density photonic integrated circuits (PICs). Due to the high index contract and low loss, SOI structures can reduce the device size. However, SOI devices possess strong polarization dependence, which may degrade the performance of optical communication systems. To overcome this drawback, various types of SOI-based polarization rotators and polarizers have been proposed with long device lengths. We first propose an ultracompact polarization rotator based on an L-shaped asymmetric hybrid plasmonic waveguide. The simulation is carried out by a three-dimensional finite element method (3D-FEM, COMSOL Multiphysics) to optimize the device performance. Due to the plasmonic effect and asymmetric L-shaped waveguide, two hybrid modes with enlarged modal index difference are induced to shorten the device length. We can realize an ultrashort rotator length of 2.35μm with the polarization conversion efficiency is 99.4% and the insertion loss is 2.6 dB。 We have also proposed an ultracompact TM polarizer based on a double hybrid plasmonic waveguide which only supports TM mode between two silicon dielectric waveguides. Meanwhile, the TE mode is cutoff on the TM polarizer. The simulation is also carried out by the 3D-FEM to analyze the polarizer properties and optimize the polarizer. The optimized design shows that, as the device length is 1 µm, we can obtain the extinction ratio and insertion loss are 17.2 dB and 1.92 dB, respectively. We successfully utilize the hybrid plasmonic waveguide to design ultrashort polarization rotator and polarizer. The device length of our proposed polarization rotator and polarizer are very short compared to the conventional silicon-based polarization devices, which can help to realize high-density PICs.

碩士
國立彰化師範大學
電信工程學研究所
106
In the first part of this thesis, a broadband waveguide polarizer with novel corrugated structures is discussed. We propose a new corrugated structure and analyze the phase delay affected by the parameters of the unit cell of this corrugated structures in the waveguide of size . Measurement results show that the phase difference is between from 84 to 90 degrees and the return loss is better than 20 dB from 19 GHz to 31.2 GHz. In the second part, we propose the four-way waveguide power divider using Schwarz-P minimal surface structure. The simulation result shows that the signal can equally be divided into four different ports except the opposite port.

This thesis prompt a theoretical analysis of the hybrid plasmonic waveguide (HPWG) and a TE-pass polarizer based on HPWG has been designed, fabricated and characterized. A combination of low propagation loss, high power density, and large confinement is useful for many applications. The analysis results in this thesis show that the HPWG offers a better compromise between loss and confinement as compared to pure plasmonic waveguides. Another interesting property of the HPWG is its polarization diversity. In the HPWG the transverse electric and the transverse magnetic modes reside in different layers. We have designed a very compact hybrid TE-pass polarizer using this property. The polarizer was fabricated and characterized. The device shows low insertion loss for the TE mode with a high extinction ratio at telecommunication wavelength range for a 30 µm long HPWG section. Its performance compares favorably against previously reported silicon based integrated optic TE-pass polarizers.

碩士
國立臺灣科技大學
電子工程系
107
In this thesis, waveguide polarizers fed by the planar transmission line and substrate-integrated waveguide power dividers are proposed. The details of the content are described below. In Chapter 2, circular waveguide and rectangular waveguide polarizers fed by the planar transmission line are proposed. Since the antisymmetric tapered probe is used to feed the waveguide polarizers with double ridges and slots directly, the planar transmission line to waveguide transition and the polarizer can be integrated directly, reducing the circuit size. The circular waveguide and rectangular waveguide polarizers are implemented on the Rogers® RO4003 substrate of thickness 32 mil. The fractional bandwidths, in which the reflection coefficient is smaller than -10 dB, of these two polarizers are 24.6% and 35.1%, respectively, covering part of the X-band (8.2-12.4 GHz). The bandwidth of 3 dB Axial Ratio are 12.7% and 30.5%, respectively while the 909 phase shift are 14.6% and 9.2%, respectively. In Chapter 3, several substrate-integrated waveguide power dividers implemented on the single layer Rogers® RO4003 substrate are proposed. First of all, the T-junction implemented with the 50-Ω microstrip line is used to achieve a broadband response of the reflection coefficient. Successively, the T-junction implemented with the low impedance microstrip line is used to reduce the circuit size of the power divider. Besides, the Wilkinson power divider is used to improve the isolation between the output ports of the power divider. The results are shown below. The substrate-integrated waveguide power divider using the 50- microstrip line T-junction has a -15-dB reflection coefficient bandwidth of 37.9%, covering most bandwidth of the S-band (2.60-3.95 GHz). In this bandwidth, the transmission coefficient is smaller than -3.24 dB and the isolation is larger than -6.57 dB. The substrate-integrated waveguide power divider using the low impedance microstrip line T-junction has a -15-dB reflection coefficient bandwidth of 46.5%, covering the whole S-band (2.60-3.95 GHz). In this bandwidth, the transmission coefficient is smaller than -3.24 dB and the isolation is larger than -5.57 dB. In addition, the area occupied is much smaller than that of the substrate-integrated waveguide power divider using the 50- microstrip line T-junction. The substrate-integrated waveguide power divider using the Wilkinson power divider has a -15-dB reflection coefficient bandwidth of 34.7%, covering most bandwidth of the S-band (2.60-3.95 GHz). In this bandwidth, the transmission coefficient is smaller than -3.27 dB and the isolation is enhanced to be than -33.69 dB. In order to reduce the cost, the single layer FR4 substrate is used to implement the power dividers mentioned above. The performance of the power dividers implemented with the FR4 substrate is similar to the performance of the power dividers implemented with the Rogers® RO4003 substrate except that the transmission coefficient would be deteriorated since the substrate loss of the FR4 substrate is larger than that of the Rogers® RO4003 substrate.

碩士
國立清華大學
電機工程學系
85
The performance of optical metal-clad waveguide polarizers is analyzed in this study with a view to optimizing the extinction ratio. A condition forwhich power of the TM mode is completely attenuated is for the frist time identified here. In general, such a condition corresponding to an infinitelyhigh extinction ratio can be met for a wide range of buffer layer thicknesses by selection of metal film thicknesses and polarizer lengths. When a very thick ( i.e., semi-infinitely thick ) metal film is used, the aforementioned condition can be met with a properly chosen buffer layer thickness and polarizer length. The effect of dielectric-cover-layer thickness on the polarizer performance is also included in the discussion here. From an example of thin- metal-clad wave guide polarizer, we show that an infinitely high extinction ratio canbe realized for a wide range of cover layer thicknesses by selection of metalfilm thickness and polarizer length. The numerical results show that all the polarizers designed here for realization of infinitely high extinction ratioshave either quite low or reasonably acceptable attenuations for the TE mode.

碩士
國立中興大學
物理學系所
102
We design three different waveguide polarizers using the hybrid plasmonic waveguide concept to shrink the component size while maintaining good transmission performance. The first one we propose is a TE-pass polarizer by changing structure periodically in order to quickly loss TM polarization. When the element lengths are L = 800, 1800 and 3000 nm, the polarization extinction ratios are 10 dB, 15 dB and 19.14 dB, respectively, with a low insertion loss. The second polarizer is a bent waveguide structure. We separate TE mode from TM mode by turning TE mode ninety degrees along the bent waveguide but keep the TM mode propagating straight. For the radius of curvature R = 250 nm, the extinction ratio of TE and TM polarizations are 10.7 and 14.2 dB, respectively, and the insertion loss are as low as 0.27 dB and 0.19 dB for TE and TM polarizations, respectively. With this design, the device has a footprint as small as 375×375 ?nm?^2. The third one is with oblique propagation structure. The TE mode is designed to be oblique propagation and the TM mode propagates straight. The area of this design is 850×1000 ?nm?^2 with the extinction ratios 17.1 and 19.3 dB and the insertion losses 0.32 dB and 0.88 dB for TE and TM polarizations, respectively.

碩士
國立中央大學
電機工程學系在職專班
101
This thesis describes the design with simplification structure and fabrication on the same plane of FR-4 substrate. At first studying the single band CPW-fed slot antenna, and then designing of proposed broadband circular polarization CPW-fed slot antenna, which is achieved by an asymmetry ground plane makes the adjacent resonant mode to merge into a wide operation bandwidth and etching C-shaped ground strip on the edge of left side of ground plane to offer the current path, two orthogonal electric fields with a 90°phase difference for exciting a circular polarization radiation wave. On the other hand, a C-shaped slot is embedded at the bottom right corner of ground plane. It is used for broadband AR and impedance matching. The measured impedance bandwidth (VSWR 2) is 0.92 GHz (46% relative to the center frequency at 2 GHz). The 3-dB axial ratio bandwidth (ARBW) is 0.65 GHz (32.5% relative to the center frequency at 2 GHz), and antenna peak gain is 3.31 dBi with variations of less than 1 dBi. This antenna is suitable for wireless communication system (1.71－2.17 GHz) and navigation system (1.57－1.61 GHz).

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.

碩士
逢甲大學
電機工程學系
106
This paper focuses on new type antennas of harmonic suppression with circular polarization. The π-shape resonator can be used to suppress the high-order frequency. They can be applied to wireless local area networks WLAN 5.8 GHz (5.725 GHz to 5.825 GHz) and DSRC 5.9 GHz (5.85 GHz to 5.925 GHz). A coplanar waveguide-fed circularly polarized antenna with harmonic suppression is initially proposed (proposed antenna 1). The antenna size is 30 mm× 30 mm× 0.762 mm. By adding two quadrant arc-shaped perturbed elements into the circular patch antenna, a circularly polarized (CP) band is excited from 5.85 GHz to 5.925 GHz. The π-shape resonator is loaded at the end of coplanar waveguide feed and coupled with the circularly polarized patch antenna. The measured 10-dB bandwidth and CP bandwidth were 660 MHz (5.67 GHz～6.33 GHz) and 75MHz (5.85 GHz～5.925 GHz), respectively. The measured maximum antenna gain and antenna efficiency were 5.5 dBic and 84.1%, respectively. The design of proposed antenna 2 is based on the architecture of proposed antenna 1. In order to increase the CP bandwidth without changing the structure of the resonator, a crescent slot is embedded into the ground plane. This design can increase the CP bandwidth to 5.72 GHz～5.88 GHz, which can cover the WLAN 5.8 GHz band (5.72 GHz～5.85 GHz). The measured 10-dB bandwidth was 850 MHz (5.7 GHz～6.55 GHz). The measured maximum antenna gain and antenna efficiency were 3.9 dBic and 81%, respectively.

碩士
淡江大學
電機工程學系碩士班
106
With the rapid progress in wireless communication, adaptive or reconfigurable antenna are required to meet the changing in environmental conditions to achieve the highest performance of wireless communication. Therefore, reconfigurable antennas like frequency switchable antennas, pattern reconfigurable antennas, or polarization switchable antennas have attract many attentions these years. A frequency switchable antenna can avoid frequency deviation, or change its frequency band to the desired communication system. A pattern reconfigurable antenna can change its radiation pattern to be omnidirectional or to be end-fire according to the applications, or steer the high directive radiation pattern to the target. A polarization switchable antenna can change its polarization of wave to vertical polarization, horizontal polarization, right-handed circular polarization, or left-handed circular polarization. The advantage of this type of antenna is that it can eliminate multipath fading, or double the system capacity through a frequency reuse. In the literature, there are many polarization reconfigurable antennas have been proposed. In order to realize the antenna using printed circuit board, most of the antenna structure are based on microstrip antenna, whose antenna gain is relatively low. In this paper, a novel polarization switchable antenna based on substrate integrated waveguide is presented. The polarization of the proposed design can be switched between right-handed circular polarization and left-handed circular polarization. The switching of different polarizations can be achieved by employing the PIN diodes and changing the ON/OFF state of it. The proposed design is also measured and simulated to validate the proposed concept. The radiation characteristic of the proposed design is not sensitive to the size of the ground plane, also, the compact and single port design makes it more suitable for array configuration.

Due to high demand for planar structures with low loss, a considerable amount of research has been done to the design of substrate integrated waveguide (SIW) components in the mm-wave and microwave range. SIW has many advantages in comparison to conventional waveguides and microstrip lines, such as compact and planar structure, ease of fabrication, low radiation loss, high power handling ability and low cost which makes it a very promising technology for current and future systems operating in K-band and above. Therefore, all the work presented in this dissertation focuses on SIW technology. Five di erent antenna systems are proposed to verify the advantages of using SIW technology. First, a novel K-band end- re SIW circularly polarized (CP) antenna system on a single layer printed-circuit board is proposed. A high gain SIW H-plane horn and a Vivaldi antenna are developed to produce two orthogonal polarizations in the plane of the substrate. CP antennas have become very popular because of their unique characteristics and their applications in satellites, radars and wireless communications. Second, a K-band front-end system for tracking applications is presented. The circuit comprises an antenna array of two Vivaldi antennas, a frequency-selective power combiner, and two frequency-selective SIW crossovers, which eliminate the need for subsequent ltering. The integration of monopulse systems in planar, printed circuit SIW technology combined with the added bene ts of ltering functions is of great importance to the antennas and propagation community. Third, a phased array antenna system consisting of 24 radiating element is designed as feed system for reflector antennas in radio astronomy applications. A Ku-band antipodal dipole antenna with wide bandwidth, low cross-polarization and wide beamwidth is suggested as the radiating element. Forth, four di erent right-angled power dividers including in-phase and out-of-phase dividers as feed systems for antenna arrays are introduced. TE10 - to - TEq0 mode transducers are used for obtaining two, three, and four output dividers with phase control ability at K- and Ka-band. This feature is practical, for instance, when designing tracking systems since they are employed to obtain controllable phase distributions over the output ports. Fifth, a Ku-band beam steering antenna system which is applicable to use for wireless communications, radar systems, and also 5G applications is proposed. This antenna system uses variable reflection-type phase shifters which electrically steer the beam over a 50-degree scan range. Therefore, the SIW technology's reliability and also promising behavior in the microwave frequency range is proven for di erent applications.
Graduate

碩士
國立交通大學
電信工程研究所
99
Recently, a new technique called the substrate integrated waveguide (SIW) has been proposed and developed as relatively attractive for high-power, low-cost, high-quality, and high-density integration of micro- and millimeter-wave components. Characteristics of such SIW structures were similar with the conventional rectangular waveguides. This thesis mainly utilizes this technology to design circular polarized antenna and microwave component. The first topic of this thesis is designing a two-whole SIW coupler and then applying it to design a circular polarized antenna. For enhancing the circular polarized bandwidth of traditional polarized antenna, this thesis utilized the characteristics of SIW multihole combined with the methods of slot-coupled antenna to achieve the purpose of enhancing the circular polarized bandwidth. The second topic of this thesis is using a corner-coupled resonator to design a filter and then applying it to design a diplexer , providing a novel way in the field of designing a compact diplexer.

碩士
國立交通大學
電信工程研究所
99
The thesis based on the concept of the waveguide coupling employs resonant slots to couple power from the main waveguide to crossed branch waveguides. An antenna array which is composed of the circularly polarized (CP) four-slots radiated elements can result in a high gain at the broadside direction. The side lobe level (SLL) can be greatly reduced by appropriate design. In the substrate integrated waveguide (SIW), the guided wavelength is less than the wavelength in air. When the array spacing is around a guided wavelength, the grating lobe can be avoided. The circularly polarized element consists of two orthogonal rectangular slots pair. One rotated with positive angle excites zero phase of electric field and the other one with negative angle excites the ninety degrees phase of electric field. In order to achieve the varies excitations for our design, we control the length of rectangular slot. Therefore every element must be slightly off-resonance. The varies slots geometries cause the varies phase excitations. We can choose array spacing to do phase compensation to get equiphase excitations of the array element. Finally, we design the circularly polarized array antenna at the 12GHz frequency band which can be applied to the satellite antenna. It has better performance than traditional waveguide, especially high gain, high directivity and more compact size.

Diluted magnetic semiconductors in their paramagnetic phase exhibit a giant Zeeman response. This effect can be used in conjunction with external inhomogeneous magnetic fields to engineer spin-polarized charge-carrier eigenstates with certain desirable features. In this thesis, we solve Schrodinger’s equation numerically and examine the charge-carrier wavefunctions in DMS waveguides in the presence of a highly inhomogeneous external magnetic field from an infinitely long rectangular nanomagnet. The low-energy eigenstates are found and their dependence on various parameters, such as size of the nanomagnet, thickness of the DMS waveguide, strength of coupling between the charge-carriers and the magnetic spins in the semiconductor, and addition of other external magnetic fields, is characterized. This geometry is shown to be ideal for creating spin-polarized currents under the nanomagnet’s edges.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

碩士
國立交通大學
電信工程系所
97
Conductor-backed coplanar waveguide (CBCPW) exists two dominant modes including CPW and parallel plate modes with no cutoff frequency. The latter one causes the power leakage into transverse direction. We use the characteristic to design it as a good transmission line. Implementing the full wave analysis (Spectral Domain Approach) on the CBCPW structure, we can acquire the information that the surface wave propagates along a particular angle relative to the main CPW line. So, we etch rectangular slots along the angle on the two side ground planes. Because the slots are separated one guided wavelength, they are excited in the same phase. If the long dimension of the slot is significantly longer than the wide one and approximately equals to a half of guided wavelength, the slots fed by CBCPW can radiate power efficiently. Finally, we derive a broadside radiation pattern. Modern satellite communication systems use circular polarization (CP) to maximize the polarization efficiency. We use the sequential rotation feeding method to produce circular polarization antennas with linearly polarized elements. The antenna for direct broadcast from satellites (DBS) is operated at 12 GHz and asked for high gain and efficiency. We design our antenna to operate at this frequency. Finally, we have the measured radiation pattern with 24.84 dBiC and the measured axial ratio 3 dB bandwidth with 330 MHz.

碩士
國立臺灣大學
應用力學研究所
93
When light beam propagates in the waveguide, the optical phase is influenced by the boundary index and thickness variations. Applying the phase modulation method in the configuration, the optical phase can be retrieved from the interference fringes. This technique combining the waveguide and the interferometry is so called “waveguide interfermetry”. It offers more information to resolve bio-sample parameters because both TE and TM polarizations are available. Therefore, it is very suitable to being applied to bio-molecules interactions measurement. In this thesis, a newly developed dual-polarization waveguide interferometry system is developed. The Mach-Zehnder Interferometry based optical configuration includes the newly developed waveguide chip, the sample and the reference light beams equipped with different polarizations, the phase modulation mechanism by combining quarter wave plate and analyzer, CCD, IMAQ card, and LabVIEW program to acquire the signal. Moreover, integrating the analog temperature control system in this optical biochip system further reduces the influence of the environmental disturbance. The motivation of this dissertation is to solve some problems faced by SPR and ellipsometry detection techniques in bio-tech analysis. Due to generic optical configuration limitations, SPR technique can only adopt TM polarization detection and thus may have less information to retrieve parameters needed to explore the complex bio-reactions. In ellipsometry detection, the incident light path through the bio-sample layer changes due to the bio-sample index variations, which makes it hard to determine the exact incident angle needed for inverse calculations. In order to improve shortcomings of these techniques, the dual-polarization waveguide interferometry system is developed and built during the course of this research. The incident light beam in this method can sense the bio-sample by using both TE and TM polarizations and is propagated in the waveguide without suffering variable indices when light beam penetrates across bio-sample and chip layers. Furthermore, the resolution of waveguide interferomerty is increased due to the multi-reflections exist the waveguide. The dual-polarized waveguide interferometry system has bee proved the ability to detect the bio-molecules interactions. Some ELISA interaction and regeneration experiments were completed. The Anti-IgG and IgG reaction was successfully measured. These experimental results can be converted into the complex bio-reaction information sought after by biomedical researchers. To further improve the resolution and to expand the application regime of this system, several work items were proposed, which include minimizing the optical system size, simplifying the signal detection part, reducing the waveguide chip cost, and integrating the flow injection system. With these suggested potential improvements implemented, the dual-polarization waveguide interferometry system is expected to become even more accurate and more versatile.

碩士
國立交通大學
電信工程研究所
102
This thesis includes two parts of research. Part one of this thesis proposes a asymmetric type of coplanar waveguide antenna and part two would purpose a L-shape slot circular polarized antenna. In the first part, an asymmetric coplanar waveguide antenna is proposed. Manufacturing by 0.8mm FR-4 substrate, a 50mm*50mm size antenna can radiate at endfire derictions instead of broadside. The theory of band-pass filter is referred in making this antenna. Traditionally, making a coplanar waveguide transmission line would include a symmetric and large enough – can be seemed as infinite ground – ground plane. By letting one side of ground become as small as comparing to another side of ground. The unbalance ground plane makes one side of E-field weaker from another. The stronger side of E-field make the whole structure vulnerable to radiate. The second part of this thesis proposes an L-shape circularly-polarized slot antenna which works at two different frequencies. Slot antenna is always a good choice for making circularly- polarized antenna. In this work, the L-shape slot on the ground plane would cause two different linearly-polarized E-fields therefore it generates a circularly-polarized E-filed. By using the two 90 degree corner microstrip line feeding, the two linearly-polarized E-field become sameamplitude so the axial ratio of circularly-polarized E-field is low. The two different size of L-shape slot generate two different resonant frequency bands. One work at 1.5GHz ~ 1.7GHz (which covers GPS L1 band 1.575GHz) and another work at 2.4GHz ~ 2.5GHz(which covers WiMAX band of 2.45GHz ).This antenna can be used to receive and transmit circularly-polarized signal at two different frequency bands.

碩士
國立交通大學
電信工程研究所
99
The slotted conductor-backed coplanar waveguide antenna features high gain, and belongs to linearly polarized antenna. According to the sequential rotation feeding method, a circularly polarized array can be composed of linearly polarized elements. Therefore, the slotted conductor-backed coplanar waveguide antenna is applicable to this theory, and can compose a circularly polarized array. In this thesis, we use the technique to produce circular polarization, and improve the performance with more linearly polarized elements. The antenna for direct broadcast from satellites (DBS) is operated at 12 GHz and asked for high gain and efficiency. We design our antenna to operate at this frequency. Finally, we have the measured radiation pattern with 26.12 dBiC and the measured axial ratio 3 dB bandwidth with 1 GHz.

Student Number : 0002066T - MSc dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment
Investigations of uni-directional, horizontally polarized waveguide antennas with longitudinal slotted arrays operating at 2.45GHz and their applications to wireless local area networks (WLAN) are presented in this paper. Requirements, considerations, and limitations associated with the design process of this particular waveguide are discussed and presented. Various antenna parameters were simulated using MATLAB® and SuperNEC® software simulation programs, and were applied to a sensitivity analysis of antenna design. End-fed and center-fed antennas were designed, built, and measured at WLAN frequencies. Measured antennas had high gain above 15dBi, broad beam around the azimuth, and high efficiency, but were limited by their impedance dependency and narrow bandwidth. The center-fed antenna had 3dBi higher gain than the 18dBi gain of the end-fed antenna. The VSWR ratio of both antennas was less than 1:1.5 at the operating frequency. The center-fed antenna had broader azimuth and elevation patterns by 40° and 10°, respectively. The end- fed antenna had more stable gain and VSWR, 50% wider VSWR bandwidth of 100MHz, and more directional elevation pattern. The design criteria generated using waveguide theory and simulated analysis was validated by the physical design and performance of the measured antennas.