Broadband phase shifter design for phased array radar systems

Ph.DDOCTOR OF PHILOSOPH

Circuitos de Radiofrecuencia de Banda Ultra-Ancha en Tecnología Planar Integrada: Aplicación a Receptores de Seis Puertos

Se presenta el diseño, implementación y evaluación experimental de un demodulador I/Q de seis puertos analógico de altas prestaciones, capaz de operar en la banda de 3.1 a 10.6 GHz sin necesidad de técnicas de calibración. El objetivo es reducir en la medida de lo posible los requisitos tanto de la etapa de conversión analógico-digital, como de la etapa de post-procesado, lo que redundaría en una reducción sustancial de la complejidad y del coste final de este tipo de demoduladores

Wearable Antenna Design For Micropower Generation

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2009Bu çalışmada, elektromanyetik sinyallerin yoğun olarak yer aldığı ortamlardan, giyilebilir kumaşlardan tasarlanan geniş bantlı-dairesel polarizasyonlu anten aracılığı ile elektromanyetik enerjiyi depolama gerçekleştirilmiştir. Ortamdaki elektromanyetik enerjiyi kullanılabilir elektrik enerjisine dönüştürmek için anten ve doğrultucu devreye ihtiyaç vardır. Bu amaç doğrultusunda anten tasarımı ele alınırken; elektromanyetik enerjinin ortamda en yoğun bulunduğu GSM 900, GSM 1800 ve W-LAN bantlarını kapsayan, çok rezonanslı, dairesel polarizasyonlu mikroşerit anten tasarımı gerçekleştirildi. Antenin topladığı sinüzoidal sinyali doğru akıma çevirecek doğrultucu devre için, eşik değeri diğer diyotlara göre çok düşük, Schottky diyot tercih edildi. Kapasiteler ve Schottky diyotlardan oluşan doğrultucu devre, devre elemanlarında oluşan kayıpları en aza indirgemek için en basit şekilde seçildi. Uygulamanın bir sonraki adımında, antenin kolayca insan vücudu üzerinde rahatsızlık vermeden taşınabilmesi için; anten, giyilebilir, esnek, iletken ve iletken olmayan kumaşlarla yeniden tasarlandı. Bu çalışmada, giyilebilir kumaşlar araştırılırken farklı seçenekler ele alındı. Ölçümler, iki farklı özellikte iki çeşit kumaş için yapıldı. Aynı zamanda anten, göğüs kafesi profili göz önüne alınarak büküldü ve insan vücudunun anten parametrelerine etkisi araştırıldı.In this study, electromagnetic energy harvesting is presented by using of wideband-circularly polarized antenna which is made out of wearable fabrics. In order to convert the electromagnetic energy in the environment to electrical energy, a proper antenna and a rectifier are needed. Considering this, the antenna was designed to be a circularly polarized microstrip antenna with multi-resonance, including GSM 900, GSM 1800 and W-LAN bands, in which the electromagnetic energy is intensively found in the environment. For the rectifier circuit which is supposed to convert the sinusoidal signal collected by the antenna into direct current, Schottky diode, whose threshold voltage is lower than the others, was preferred. The rectifier circuit, which consists of capacitors and Schottky diodes, was chosen as simple as possible in order to minimize the loss occurring in the circuit elements. At the next step of the application, in order the antenna to be carried comfortably on human body, it was redesigned using wearable, flexible, conducting and dielectric fabric. In this study, researching the kinds of wearable fabric, different alternatives were discussed. The simulations were carried out for two different kinds of fabric. The antenna was bent considering the rib cage profile, and the effects of the human body to the antenna parameters were investigated.Yüksek LisansM.Sc

Broadband design on dual and circularly polarized antennas for wireless communication systems

Master'sMASTER OF ENGINEERIN

Substrate Integrated Waveguide Devices and Receiver Systems for Millimeter-Wave Applications

RÉSUMÉ La très forte congestion du spectre radiofréquence alloué aux fréquences RF et micro-ondes pour les communications sans fil d’aujourd’hui motive ce travail de recherche qui se consacre aux bandes millimétriques pour lesquelles d’avantages d’allocations spectrales sont disponibles, et qui est particulièrement intéressante pour le transfert à très haut débit. Comparé aux autres technologies de ligne de transmission, le Guide Intégré au Substrat (GIS) montre des avantages très attractifs comme un faible profil, un faible coût, un haut facteur de qualité (facteur Q), de faibles pertes d’insertion... Ce dernier a gagné beaucoup d’attention récemment grâce à ces caractéristiques favorables pour la conception de circuits et systèmes millimétriques. Le sujet de ce doctorat concerne deux tâches de recherche distinctes : la première est dédiée à l’investigation et à la conception de composants et d’antennes GIS innovants pour une possible application en ondes millimétriques; la seconde se consacre à la mise au point et à la démonstration de systèmes de réceptions millimétriques de tailles compactes, faibles pertes, à haut niveau d’intégration et hautes performances. Les chapitres 1 à 4 se concentrent sur l’exploitation et l’investigation, un à un, de composants GIS pour lesquels un nombre de concepts originaux et innovants de structures est proposé et démontré. Dans le chapitre 5, les architectures classiques et les paramètres des systèmes de réception sont introduits, puis utilisés pour la conception de systèmes de réceptions millimétriques dans les chapitres suivants. Du chapitre 6 au chapitre 8, des systèmes submillimétriques et millimétriques basés sur le GIS sont démontrés. Les contributions majeures de cette thèse sont les suivantes : Une structure balancée large bande inhérente peut être obtenue en imprimant un circuit sur deux faces d’un substrat GIS. Ainsi, un balun planaire large bande GIS implémenté sur un circuit imprimé (ou PCB, pour Printed Circuit Board) simple couche est proposé et présenté, suite auquel une nouvelle transition large bande de ligne microruban à ligne parallèle est démontrée. Avec cette transition proposée comme réseau d’alimentation, une nouvelle antenne large bande quasi-Yagi planaire est développée.----------ABSTRACT The heavily congested condition at the existing radio frequency (RF)/microwave spectra allocated for the today’s wireless communications motivates and expedites the research work at millimeter-wave bands where more spectrum space is available for massive data rate delivery. Compared with other transmission line techniques, the substrate integrated waveguide (SIW) platform shows attractive advantages of low profile, low-cost, high Q-factor, and low insertion loss, etc. It has gained a lot of attention recently due to its favorable features in millimeter-wave circuit/system design. The topic of this doctoral dissertation are concerned with two distinct research tasks: (1) investigating and designing innovative SIW components and antennas for possible millimeter-wave applications; (2) developing and demonstrating geometry-compact, low cost, high level of integration and high performance millimeter-wave receiver systems. Chapters 1 to 4 focus on the exploitation and investigation of individual SIW devices, in which a number of original concepts and innovative structures are proposed and demonstrated. In Chapter 5, generic architectures and parameters of receiver systems are discussed and used as a guideline for the millimeter-wave system design in the next chapters. From Chapter 6 to Chapter 8, sub-millimeter/millimeter wave systems based on SIW technique are demonstrated. The major contributions of this thesis work can be highlighted as follows:An inherent broadband balanced structure can be achieved by printing circuits on two opposite sides of an SIW substrate. According to this feature, a broadband SIW planar balun implemented on a single layer printed circuit board (PCB) is proposed and presented, following which another newly proposed broadband microstrip-to-broadside parallel stripline transition is demonstrated. With the proposed transition as the feeding network, a novel broadband printed quasi-Yagi antenna is developed. Half-mode substrate integrated waveguide (HMSIW) and quarter-mode substrate integrated waveguide (QMSIW) techniques are introduced for the purpose of miniaturizing SIW circuits and enhancing the bandwidth

Impedance Transformers

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