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Wideband and superdirective small antennas with embedded optimized loads using the characteristic modes theory

Abstract : The rapid evolution in the wireless communication systems requires more miniaturization of various electronic components in addition to the major element of the wireless technology: the antenna. In this case, an antenna occupying a limited space should be miniaturized in order to operate at the desired communication bands. However, as the electrical size of the antenna decreases, its performance degrades dramatically and it becomes limited in bandwidth, efficiency, and directivity. Classical size reduction techniques with material loading and geometry shaping of the antenna suffer from narrow bandwidth and low radiation efficiency. On the other hand, attempts to increase the directivity of small antennas using superdirective arrays are also associated with low radiation efficiency and very narrow bandwidth. To overcome these drawbacks, we propose boosting the performance of compact antennas using embedded reactive loads. By properly placing loads (active or passive) inside the antenna, it is possible to control the currents to significantly enhance the antenna performance in terms of bandwidth and directivity. Yet, for a successful loading criteria, it is mandatory to analyze the modes that are naturally supported by the antenna under study. These are called the characteristic modes, which provide deep physical insights about the behaviour of the antenna and its radiating modes. By combining this theory with and optimization algorithm, it becomes possible to optimally manipulate the currents inside the antenna using reactive loads to achieve wideband, superdirective and efficient designs.
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https://theses.hal.science/tel-01945810
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Submitted on : Wednesday, December 5, 2018 - 3:25:06 PM
Last modification on : Wednesday, April 27, 2022 - 4:24:10 AM
Long-term archiving on: : Wednesday, March 6, 2019 - 2:33:18 PM

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  • HAL Id : tel-01945810, version 1

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Hussein Jaafar. Wideband and superdirective small antennas with embedded optimized loads using the characteristic modes theory. Electronics. Université Rennes 1, 2018. English. ⟨NNT : 2018REN1S031⟩. ⟨tel-01945810⟩

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