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Title: Miniaturised dual band high impedance surfaces
Author: Saad, Rola
ISNI:       0000 0004 8501 3141
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2019
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High Impedance Surface (HIS) is an exclusive type of artificial periodic structure defined as man-made material of peculiar properties not available in nature. HIS has found ultimate applications in the electromagnetic field community due to its unsurpassed distinctive characteristics for its ability to suppress surface waves and exhibit total in-phase reflection. Research has been ongoing for decades to optimize, design and explain the physical properties of such material. Particularly, high impedance surfaces which are electrically small, multifunctional and reliable are essential requirements to accommodate the high demand of modern technology trend towards compact, efficient and multifunctional systems. This research project is focused on the design and characterization of miniaturised dual band high impedance surfaces with emphasis on inter unit cell mutual coupling. Two miniaturisation methods are discussed where both utilize an uncomplicated approach to realise a dual band system. The first miniaturisation technique incorporates surface mount capacitors and realises significantly miniature HIS. Nevertheless, mutual coupling encountered necessitated attention. Therefore, novel miniaturised gridded HIS has been proposed, which effectively suppressed mutual coupling and demonstrated potential to upgrade into multiband HIS. The second miniaturisation technique implements interdigital capacitors. The original analytical methodology to realise three different miniaturised single band interdigital HIS design prototypes have been discussed. Moreover, upgrading single band interdigital HIS into dual band interdigital HIS is possible provided that mutual coupling is taken into consideration. Therefore, the final part of the thesis discusses a novel methodology to develop robust models that predict the mutual coupling level in advance such that a miniaturised dual band interdigital HIS is realised from single band structures. More precisely, a multiple linear regression technique is employed, therefore, generating mathematical models that calculate percentage frequency displacement encountered as a consequence of mutual coupling. For a generic dual band HIS, regression models are verified in three novel miniaturised dual band interdigital high impedance surfaces, which differ in design complexity and polarization dependency.
Supervisor: Ford, Lee Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available