Astronomy constantly pushes the limits of technology in order to decipher the workings of the Universe. There is a constant need for higher resolution observations across a wide range of wavelengths, at preferably a minimal cost. The terahertz regime (lambda=100 um to lambda=1000 um) covers a region of the electromagnetic spectrum that is blocked by Earth's atmosphere, which limits observations to high altitude plane and balloon telescopes and space telescopes. These current options limit the resolution achievable due to the size of telescopes that can be launched. This dissertation investigates a new approach, the Large Balloon Reflector (LBR), where a 20 meter diameter spherical balloon can be inflated and used as a 10 meter telescope inside a larger carrier balloon. Detailed in this dissertation are design considerations for the terahertz regime and a series of scaled versions of this balloon concept where I work to develop on-axis spherical corrector designs. Chapters 1 through 6 focus on the LBR designs and their variants, including investigations for a 3 meter rooftop proof of concept model, a 5 meter test flight model, and the final 20 meter LBR. The successful modeling and proof of concepts from the LBR studies then prompted an investigation into a Terahertz Space Telescope (TST), a proposed 20 meter inflatable telescope adapted from the LBR technology. Starting with Chapter7, this dissertation explores the application of using 1 meter diameter inflatable balloons as rapidly deployable communications satellites from standard CubeSats. The concept, design and test results of an electronically steerable line feed antenna array are presented which allows for instantaneous, non mechanical pointing of a 10 GHz signal within a 500 km ground footprint. Alternative uses of the 1 meter inflatable balloon CubeSat are also discussed, such as low cost astronomical galactic plane surveys.

This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.

No description available.

The thesis deal with possibility of localization of avalanche victims. Main focus is for RF avalanche beacons. The major objects of this thesis are design and construction of this device. A large part of thesis describes design of avalanche beacon and particular steps of realization. The design take into account the compatibility with commercial beacons. The paramters of designed device are verified by testing and measurement.

GIS are geoprocessing programs that are commonly used to store and perform calculations on terrain data, maps, and other geospatial data. GIS offers the latest terrain and building data as well as tools to process this data. This thesis considers three applications of GIS data and software: a Large Scale Radio Frequency (RF) Model, a Medium Scale RF Model, and Indoor Positioning. The Large Scale RF Model estimates RF propagation using the latest terrain data supplied in GIS for frequencies ranging from 500 MHz to 5 GHz. The Medium Scale RF Model incorporates GIS building data to model WiFi systems at 2.4 GHz for a range of up to 300m. Both Models can be used by city planners and government offcials, who commonly use GIS for other geospatial and geostatistical information, to plan wireless broadband systems using GIS. An Indoor Positioning Experiment is also conducted to see if apriori knowledge of a building size, location, shape, and number of floors can aid in the RF geolocation of a target indoors. The experiment shows that correction of a target to within a building's boundaries reduces the location error of the target, and the vertical error is reduced by nearly half. / Master of Science

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Reduction in available radio frequency (RF) spectrum for use in aircraft testing has steadily increased the probability of interference. The increase in users and required bandwidth generates requirements for increased monitoring and active management of the RF spectrum. The detection of background RF emissions and monitoring of authorized users will be used by future range test engineers to make decisions on when and where to conduct test missions to minimize the probability of interference. The detection of authorized users exceeding their allotted RF spectrum as well as unknown emitters should include: the general geographic area of potential interference, and times of transmission. This paper outlines the development of a complete system for wide-band RF monitoring to identify and locate active emissions. The RF surveillance system proposed must be inexpensive, easy to maintain, support large area coverage, and monitor wide bandwidths at long range. The system should contain software for emitter identification, which will determine where the current background and authorized RF transmissions occur and how they might effect authorized transmissions, and specialized software to alert spectrum managers of potential interference scenarios in real time based upon the daily schedule.

Parmi les principaux verrous à lever pour la mise en place de l’IoT, l’un des plus difficiles concerne l’autonomie des objets. Il est en effet difficilement concevable, vu le grand nombre de composants déployés, d’intervenir sur chacun pour remplacer, ou recharger, leur batterie. Dans ce contexte ma thèse a pour objectif de proposer des solutions éco-énergétique afin de rendre tout ou partie autonome des objets communicants, type capteur. Une des solutions est de développer des récupérateurs d’énergie radiofréquences fonctionnant aux fréquences dans la bande ISM, 900 MHz et/ou 2,4 GHz. Grâce aux modules de récupération d’énergie le capteur pourra fonctionner sur une période théoriquement illimitée, grâce à un module de stockage d’énergie embarqué rechargeable. En pratique, la fiabilité de l’élément de stockage définira le temps de vie du capteur, estimé à une vingtaine d’années avec les cellules de stockage rechargeables actuelles. Les solutions existantes dans le commerce sont presque exclusivement développées sur substrat époxy (ou dérivé). Cette solution est généralement robuste et performante. En revanche la rigidité mécanique du substrat réduit l’intégration des nœuds dans notre environnement, elle devient rédhibitoire dans le cas des réseaux corporels. Afin de permettre au capteur autonome de s’intégrer plus facilement, et d’adresser notamment des applications de type biomédicales, celui-ci sera développé sur substrat souple. Cet objectif pose certains défis quant à la maitrise des procédés de fabrication et de report des composants pour les performances des parties radiofréquences / Electronics has undergone an unquestionable evolution in recent years. The progress made gives more efficient circuits and smaller, but especially more and more energy efficient. This evolution, combined with advances in the digital and IT domain, has enabled the expansion of Internet of Things (IoT) applications based on the massive deployment of autonomous wireless communicating sensors. The first generations of sensor could only work during the time of discharge of their battery. One of the proposed ways to extend the autonomy of objects is to use the ambient energy. Several technologies have been developed to optimize the energy harvesting depending on the environment of the sensor. The work of this thesis allows developing RF energy harvesters in three steps. The first part studies antennas structures compatible with the energy harvesting. Each antenna is optimized to either recover more energy or better integrate into the environment. The second step focuses on the RF / DC conversion circuit. The study of different circuits architectures, diodes and number of stages potentially relevant for our application, allowed realising circuits able to work with our antennas. Each circuit was then optimized to increase its conversion efficiency and its sensitivity. The final step was to assemble an antenna with a rectifier to characterize the complete harvester according two different scenarios: opportunistic energy harvesting and energy transfer conditions.

Este trabalho apresenta uma ferramenta para a simulação de sistemas de comunicação utilizando modelos em alto nível para cada um dos blocos empregados. A ferramenta é baseada em modelos comportamentais de blocos de Radio Freqüência (RF), o que reduz custos, tempo de simulação e permite um rápido diagnóstico de problemas precoces no projeto de um sistema de comunicação sem fio. O desenvolvimento de blocos, como o LNA (Low Noise Amplifier), o MIXER, o LO (Oscillator Local) e o PA (Power Amplifier), facilita a implementação de qualquer arquitetura de Transmissão e de Recepção. Para isso foram levados em consideração efeitos de ruído, não linearidade e ganho no modelo dos blocos. Com isto se espera que a ferramenta ajude no projeto de circuitos integrados de um sistema de blocos em cascata, onde o usuário possa selecionar, configurar e simular o sistema. Na utilização da ferramenta é indispensável um conhecimento prévio das características e especificações em nível de sistema. Assim, se poderão fazer mudanças nos parâmetros de blocos, que permitirá então analisar compromissos existentes entre ruído, ganho e distorção do sinal através de todo o caminho, antes mesmo de se ter uma resposta definitiva. A ferramenta de simulação é implementada em Simulink, que é um pacote (toolbox) de Matlab, amplamente utilizado no desenvolvimento de algoritmos e blocos de comunicação. A interação e ambiente gráfico da ferramenta facilitam o uso pelas pessoas envolvidas direta e indiretamente com o projeto de circuitos. Finalmente, para verificar a ferramenta desenvolvida foi feito um estudo de caso, onde se modelou e simulou o padrão Bluetooth. / This work presents a tool for the simulation of Communication Systems using macromodels for each block used. The tool is based on behavioral models of Radio Frequency (RF) blocks, which minimize cost, simulation time and allows a fast determination of problems in the early phases of the design of a Wireless Communication System. The development of blocks like the LNA (Low Noise Amplifier), the MIXER, the LO (Local Oscillator) and the PA (Power Amplifier), helps to implement any architecture for transmission and reception. For that, the effects of noise, non-linearity and gain in the behavioral model of the blocks were considered. With this, it is expected that the tool will help the design of integrated circuits of a system with cascade blocks, where the user can select, set up and simulate the system. In order to use the tool, previous knowledge of the characteristics and specifications of the system is necessary. In this way, it will be possible to change the parameters of blocks, allowing the analysis of tradeoffs between noise, gain and distortion of the signal through the system, before having a definite answer. The tool is implemented in Simulink, which is a toolbox of Matlab, normally used in the development of communication blocks and algorithms. The graphic environment of the tool allows a straightforward use for people involved directly or indirectly with the Circuit Design. Finally, in order to verify the developed tool, a case study was performed where the Bluetooth standard was modeled and simulated.

Este trabalho apresenta uma ferramenta para a simulação de sistemas de comunicação utilizando modelos em alto nível para cada um dos blocos empregados. A ferramenta é baseada em modelos comportamentais de blocos de Radio Freqüência (RF), o que reduz custos, tempo de simulação e permite um rápido diagnóstico de problemas precoces no projeto de um sistema de comunicação sem fio. O desenvolvimento de blocos, como o LNA (Low Noise Amplifier), o MIXER, o LO (Oscillator Local) e o PA (Power Amplifier), facilita a implementação de qualquer arquitetura de Transmissão e de Recepção. Para isso foram levados em consideração efeitos de ruído, não linearidade e ganho no modelo dos blocos. Com isto se espera que a ferramenta ajude no projeto de circuitos integrados de um sistema de blocos em cascata, onde o usuário possa selecionar, configurar e simular o sistema. Na utilização da ferramenta é indispensável um conhecimento prévio das características e especificações em nível de sistema. Assim, se poderão fazer mudanças nos parâmetros de blocos, que permitirá então analisar compromissos existentes entre ruído, ganho e distorção do sinal através de todo o caminho, antes mesmo de se ter uma resposta definitiva. A ferramenta de simulação é implementada em Simulink, que é um pacote (toolbox) de Matlab, amplamente utilizado no desenvolvimento de algoritmos e blocos de comunicação. A interação e ambiente gráfico da ferramenta facilitam o uso pelas pessoas envolvidas direta e indiretamente com o projeto de circuitos. Finalmente, para verificar a ferramenta desenvolvida foi feito um estudo de caso, onde se modelou e simulou o padrão Bluetooth. / This work presents a tool for the simulation of Communication Systems using macromodels for each block used. The tool is based on behavioral models of Radio Frequency (RF) blocks, which minimize cost, simulation time and allows a fast determination of problems in the early phases of the design of a Wireless Communication System. The development of blocks like the LNA (Low Noise Amplifier), the MIXER, the LO (Local Oscillator) and the PA (Power Amplifier), helps to implement any architecture for transmission and reception. For that, the effects of noise, non-linearity and gain in the behavioral model of the blocks were considered. With this, it is expected that the tool will help the design of integrated circuits of a system with cascade blocks, where the user can select, set up and simulate the system. In order to use the tool, previous knowledge of the characteristics and specifications of the system is necessary. In this way, it will be possible to change the parameters of blocks, allowing the analysis of tradeoffs between noise, gain and distortion of the signal through the system, before having a definite answer. The tool is implemented in Simulink, which is a toolbox of Matlab, normally used in the development of communication blocks and algorithms. The graphic environment of the tool allows a straightforward use for people involved directly or indirectly with the Circuit Design. Finally, in order to verify the developed tool, a case study was performed where the Bluetooth standard was modeled and simulated.

Atherosclerotic plaques in the bifurcation of the carotid artery vessels can pose a significant stroke risk from stenosis, thrombosis and emboli, or plaque rupture. However, the possibility of the latter depends on the structure of the plaque and its stability. So far, the assessment of such depositions, and the evaluation of the risk they pose, is not satisfactory with 3 Tesla black blood imaging. It is expected that the SNR increase at 7 Tesla, together with an appropriate and patient-safe RF coil, will result in higher resolution images that would help in better assessing the composition of atherosclerotic plaques in vessel walls. A custom-built neck array was designed and constructed, with the aim of investigating the benefits of the higher field strength using DANTE-prepared black blood imaging. A 4-channel transmit array was designed to generate the required <b>B</b>^&plus;<sub style='position: relative; left: -.5em;'>1</sub> field for the DANTE module to be used. A separate close fitting 4-channel receive array was preferred for improved SNR and parallel (receive) imaging. Geometric, active, passive as well as preamp decoupling schemes were employed for adequate isolation between the arrays and their channels. Electromagnetic simulation software, Semcad X (SPEAG, Zurich), was used for safety assessment with human phantoms (Virtual population). The <b>E</b> fields for 1 W transmission per channel were calculated for each element for a worst case SAR estimation. The transmission power limits per channel were set according to the 10g SAR limit set in IEC 60601. For simulation validation, temperature measurements and surface heat mapping were performed on a meat phantom. Finally, a healthy male subject was scanned using a protocol consisting of <b>B</b>₁ mapping, RF shimming at an ROI, and 2D and 3D DANTE prepared Gradient Echo (GRE). The worst-case heating scenario, as defined in the methods section, generated a maximum local SAR of 7.65 W/kg for 1 Watt per channel input. Thus, for 1st level mode (20W/kg max), the power limit was set at 2.6 W per channel. The heating profile was similar to that simulated and the measured temperature increase was within a &plusmn;10&percnt; margin relative to the simulation. The global SAR power limit per channel was found to be higher (i.e. more allowed power) than the worst case local SAR power limit, and thus did not impose additional power penalty. The resolution achieved was 0.6 mm isotropic for the 3D protocol and 0.6 by 0.6 by 2.5 mm for the 2D protocol. The average SNR was measured within the vessel wall location of the two carotid arteries and found to be 27&plusmn;6 for the DANTE images and for the static tissue closer to the skin the SNR was 55&plusmn;2. In conclusion, a 4Tx/4Rx coil was designed to target the carotid arteries operating under pTx mode and a black blood imaging sequence was implemented for blood signal suppression and vessel wall imaging. The initial results from the subject and phantom imaging show satisfactory blood suppression and spatial resolution.