Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503261
Title: Low SAR ferrite handset antenna design
Author: Kitra, Maria
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 2006
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Abstract:
The purpose of this project was the study of electrically small material coated antennas. In particular the use of a hybrid dielectric-ferrite material was examined, compared to dielectric alone, and ways it can improve antenna performance. The benefits resulting from the inclusion of ferrite were examined using both analytical and experimental methods. Initially a spherical analytical mathematical model was developed, to examine antenna efficiency, bandwidth and Specific Absorption Rate (SAR) in terms of different mixtures of relative permittivity ε, and permeability μr. The theoretical model was then validated through a numerical transmission line matrix (TLM) simulation tool, applied to spherical and rectangular resonator geometries. It was observed that a material with equal values of relative permittivity and permeability in combination with specific positioning of the antenna in relation to the head, can give rise to the definitive small-size, high efficiency, high bandwidth, low SAR antenna. Three different ferrite loaded materials were obtained and used to construct three material coated monopole sample antennas. Efficiency and SAR measurements of these antennas showed good agreement with the simulation results and confirmed the accuracy of the simulation tool. Having established the advantages of using the hybrid material, further simulation work was undertaken, which optimised the material loaded resonator design and integrated it into a typical handset. Its attributes were successfully translated into three innovative multi-band handset antenna designs, covering the GSM 1800, 1900, UMTS and Bluetooth bands, with a SAR value reduced by 88% compared to conventional phones and a high efficiency. Finally, a tri-band antenna design was also developed, utilizing currently available lossy ferrite material.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.503261  DOI: Not available
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