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Antennas For Handheld Satellite Personal Communicators.

Agius, Andreas-Albertos. (1999) Antennas For Handheld Satellite Personal Communicators. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

The project presented in this thesis examines the Quadrifilar Helix (QHA) as the most appropriate antenna for satellite personal communication network (SPCN) mobile handset communicators. The research aimed at approaching the antenna issue from different angles in order to illuminate all its dimensions The SPCN poses new challenges for the antenna designer. The antenna becomes a crucial part of the communication link since the relative positions between the two ends (user and satellite) changes continuously. The antenna not only has to be as small as those on GSM handsets but also has to fulfil very demanding specifications of shaped radiation pattern with hemispherical coverage, circular polarisation and wide bandwidths. A set of requirements concerned both the operating system and the antenna itself are used as the basis of the study. The requirements constitute a criterion for selecting the most suitable antenna type for a given system. Different antenna groups fulfilling some of the SPCN requirements were investigated and the result was the selection of the family of helical antennas and in particular the Quadrifilar Helix Antenna (QHA). The QHA was studied in depth, yielding particular contributions in the following areas: Investigation by simulations and measurements of the performance capabilities of the QHA and creation of design guidelines which can be used for creating prototypes. Theoretical analysis of the QHA. The modes which are exited on this structure are presented and close form expressions for the far fields of the axial mode are formulated. A rational technique for deriving SPCN antenna specifications based on the communication environment in which the antenna will operate including the satellite system, physical environment and user interaction. This resulted in a new parameter (Effective Statistical G/T, ESGuT) that can describe the overall performance of a satellite system. Antenna designs for given specifications: A set of prototypes are designed and built based on the new ESGuT technique for particular satellite system. Different optimisation methods are also developed such as the use of loading rings and the conical QHA based on the Archimedean spiral. The work concludes with the idea of an Intelligent QHA which can adapt its performance to changes of the communication environment in order to optimise the link dynamically.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Agius, Andreas-Albertos.
Date : 1999
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1999.
Depositing User : EPrints Services
Date Deposited : 24 Apr 2020 15:27
Last Modified : 24 Apr 2020 15:27
URI: http://epubs.surrey.ac.uk/id/eprint/855022

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