Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/134584
Type: Thesis
Title: Flexible Transmission Lines and Asymmetrically Counter-Poised Monopoles
Author: Govender, Deshan
Issue Date: 2022
School/Discipline: School of Electrical and Electronic Engineering
Abstract: In the pursuit of miniaturised antennas and flexible transmission lines, several techniques have been explored in the open literature to address physical aspects of size, weight, flexibility and electrical reconfigurability, all whilst sustaining a reasonable degree of electrical operation. In the first part of this thesis, these themes are further explored with transmission lines, through the experimentation of transmission lines that use standard, readily available materials of a conformal nature, that would appreciably suit our context of operation. Two distinct types of transmission lines are designed, simulated, investigated and reported on. In the second half of this thesis, we explore asymmetrical antenna design in relation to antenna miniaturisation, aiming at creating a design method for this type of antennas. The first transmission line examined in the first part of the thesis, is what we now refer to as a Wire-Over-Ground-Plane transmission line. Structurally, this is standard gauge wire, placed over a polyimide sheet beneath which exists ground plane. A model of this transmission line is created and thereafter numerically simulated. A rough prototype of this design was created to validate operation. Thereafter, proposed is the design with realistic simulations of a branch-line coupler and modified Marchand balun, using this technology. The second transmission line created, is a stripline transmission line constructed primarily from fleece and a conductive textile. Once more, this structure is numerically simulated to validate operation prior to construction. Thereafter a number of samples are created to explore the physical robustness of the connection, through the application of mechanical stress and strain of varied transmission line constructions. In the second part of the thesis three antennas were created taking an asymmetrical approach to antenna realisation. The first Counter-Poised monopole antenna is experimentally realised by replacing one of the dipole arms with a coil of equivalent inductance. Decent performance here led to a second antenna design that builds on the first asymmetrical design, implementing a planar integrated balun into the feed-structure and developing a planar counter-poise fabricated on a circuit board. The third antenna design, builds further on the second design by adding a frequency reconfigurability feature through the addition of active circuit elements to the counter-poise. As we worked from developing the experimental antenna to realising the frequency reconfigurable variant, we have sought to understand the principle of operation and establish a design method which has allowed for the development of an advanced reconfigurable variant. The counter-poise is the fulcrum of all three asymmetrical antennas designed here, so a thorough grasp on its design and operation is required to ensure adequate antenna operation. In summation, this thesis develops ideas and realisations of flexible transmission lines using standard off-the-shelf components as well as conductive textiles and clothing. Further, asymmetrical antenna design techniques are explored leading to antenna miniaturisation. Thereafter, design methods are developed to aid in planar fixed-frequency implementation, whereupon a more advanced frequency reconfigurable variant is created.
Advisor: Fumeaux, Christophe
Dissertation Note: Thesis (MPhil) -- University of Adelaide, School of Electrical and Electronic Engineering, 2022
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
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