Search for dissertations about: "dipole antennas"
Showing result 16 - 20 of 25 swedish dissertations containing the words dipole antennas.
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16. Ultra-wideband Antenna and Radio Front-end Systems
Abstract : The number of wireless communication applications increase steadily, leading to the competition for currently allocated frequency bands. Pressure on authorities around the world to permit communications in higher and wider frequency ranges to achieve higher wireless capacity than those existed in the past has resulted in several new specifications. READ MORE
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17. Systematic Antenna Design Using the Theory of Characteristic Modes
Abstract : The day Faraday moved a magnet in and out of a wire loop and detected the time-varying magnetic field, the first wireless transmitter / receiver system was created and the world was changed forever. However, it took almost fifty years for Heinrich Hertz to use Maxwell's equations and Faraday's insights in his professorship at Karlsruhe to create the first electromagnetic wireless communication system using a spark gap dipole transmitter and a loop antenna-based receiver. READ MORE
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18. Antenna array systems : electromagnetic and signal processing aspects
Abstract : A simple and commonly used model of an array antenna consists of identical sensors, which are equidistantly located along a line. But in reality the array antennas do not look this way. The elements are not perfectly positioned, and sometimes they are even placed on a curved surface (conformal arrays). READ MORE
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19. Phased-Array-Fed Reflector Antenna Systems for Radio Astronomy and Earth Observations
Abstract : Dense Phased Array Feeds (PAFs) for reflector antennas have numerous advantages over traditional cluster feeds of horns in a one-horn-per-beam configuration, especially in RF-imaging applications which require multiple simultaneously formed and closely overlapped beams. However, the accurate analysis and design of such PAF systems represents a challenging problem, both from an EM-modeling and beamforming optimization point of view. READ MORE
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20. Cold-Electron Bolometers fabricated with Direct Write Technology for Microwave Receiver systems
Abstract : This thesis concerns the development of microwave detector technology for cosmology instruments and THz imaging, including fabrication of SIN tunnel junctions for thermometry and bolometric detectors, and also phase switch circuits as a part of integrated microwave receiver systems. Cold-Electron Bolometers (CEB) based on Superconductor-Insulator-Normal metal (SIN) tunnel junctions have been developed for employment in sub-millimeter astronomical receivers. READ MORE