Search for dissertations about: "material antenna"
Showing result 1 - 5 of 36 swedish dissertations containing the words material antenna.
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1. 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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2. Shape and material optimization for antenna applications
Abstract : In this thesis, a gradient-based method for shape and material optimization fortwo antenna applications is presented: minimization of the active reflectioncoefficient for conformal array antennas; and minimization of the totalscattering cross section for cylindrical scatterers. The sensitivity of theobjective function with respect to changes of the shape and material of the geometry isexpressed in terms of the original field problem and an adjoint field problem. READ MORE
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3. Integral Identities for Passive Systems and Spherical Waves in Scattering and Antenna Problems
Abstract : Sum rules and physical limitations within electromagnetic theory and antenna theory have received significant attention in the last few years. However, the derivations are often relying on application specific and sometimes unsupported assumptions, and therefore a mathematically rigorous and generally applicable approach seems timely. READ MORE
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4. Decoupling and Evaluation of Multiple Antenna Systems in Compact MIMO Terminals
Abstract : Research on multiple antenna systems has been a hot topic in recent years due to the demands for higher transmission rate and more reliable link in rich scattering environment in wireless communications. Using multiple antennas at both the transmitter side and the receiver side increases the channel capacity without additional frequency spectrum and transmitted power. READ MORE
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5. 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