Bandwidth enhanced sub-GHz wristwatch antennas for wireless body sensor network applications

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dc.availability.bitstreamembargoed
dc.check.date2024-09-30
dc.contributor.advisorBuckley, Johnen
dc.contributor.advisorO'Flynn, Brendanen
dc.contributor.authorKumar, Sanjeev
dc.contributor.funderEnterprise Irelanden
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderEuropean Regional Development Funden
dc.contributor.funderIDA Irelanden
dc.contributor.funderVistaMilk SFIen
dc.date.accessioned2022-02-03T15:18:25Z
dc.date.available2022-02-03T15:18:25Z
dc.date.issued2021-08-22
dc.date.submitted2021-08-22
dc.description.abstractWith recent advances in wearable wireless sensor technology, the demand for smart wristwatches is growing rapidly due to their widespread adoption in applications such as smart health monitoring, security and fitness tracking. At the present time, the majority of wristwatch devices use the 2.45 GHz band due to the widespread availability of Bluetooth and Wi-Fi wireless technologies. Recently, the use of Sub-GHz frequencies for wearable systems has also gained interest due to the emergence of wireless technologies such as LoRaWAN and Sigfox that have the potential for long-range wireless communications. However, the design of antennas for Sub-GHz wristwatch devices poses challenges due to issues such as practical size constraints and the requirement for the use of electrically small antennas. In addition, the presence of the human body in close proximity to the antenna also poses design challenges due to its effect on the key antenna characteristics. This thesis presents the development of four new Sub-GHz wristwatch antennas, with the key focus on addressing the bandwidth limitation challenge associated with state-of-the-art Sub-GHz wristwatch antennas. The research hypothesis for this work focuses on the use of a dual-radiator approach to enhance antenna bandwidth performance. In the first contribution, a novel 915 MHz wristwatch planar inverted-F antenna (PIFA) is designed using a dual-radiator approach for impedance bandwidth enhancement. The approach of using dual radiators has not been reported previously for Sub-GHz wristwatch antennas. This antenna demonstrates the highest peak realized gain and the second highest radiation efficiency for Sub-GHz wristwatch antennas reported in the literature. In the second contribution, a new 915 MHz wristwatch PIFA design printed on a flexible PCB substrate is reported, which also uses a dual-radiator design approach. This antenna features one of the most compact Sub-GHz wristwatch antenna designs and the achieved performance compares well to the literature in terms of impedance bandwidth, peak realized gain and radiation efficiency. In addition, a second iteration of this antenna is also designed for operation in the 868 MHz band. This 868 MHz antenna is directly printed on the inside surface of a plastic enclosure using laser direct structuring (LDS) technology and demonstrates a similar impedance and radiation performance as that of the 915 MHz antenna. Finally, in the third contribution, a significant enhancement of the impedance bandwidth is achieved using a modified feed structure to excite dual resonant responses that can be independently tuned to maximize the impedance bandwidth by 107 % when compared to the first generation 915 MHz antenna. The excitation of two adjacent resonant frequencies has not been previously reported for Sub-GHz wristwatch antennas in the literature. An equivalent circuit model for this antenna is also derived to explain the impedance bandwidth enhancement mechanism. Another key contribution of this work includes the development of a new equivalent transmission line model to accurately predict the antenna impedance characteristics with greatly reduced computation time compared to electromagnetic (EM) simulation. The outcomes of this thesis contribute to advancing the state-of-the-art in bandwidth enhanced Sub-GHz wristwatch antennas for wireless body sensor network applications.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationKumar, S. 2021. Bandwidth enhanced sub-GHz wristwatch antennas for wireless body sensor network applications. PhD Thesis, University College Cork.en
dc.identifier.endpage148en
dc.identifier.urihttps://hdl.handle.net/10468/12522
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectEnterprise Ireland, IDA Ireland (Grant IP20170559)en
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Research Centres/13/RC/2077/IE/CONNECT: The Centre for Future Networks & Communications/en
dc.relation.projectEnterprise Ireland (“Holistics DTIF project” under Grant EIDT20180291)en
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Research Centres/12/RC/2289/IE/INSIGHT - Irelands Big Data and Analytics Research Centre/en
dc.relation.projectEuropean Regional Development Fund (Ireland’s European Structural and Investment Funds Programmes 2014-2020)en
dc.relation.projectVistaMilk SFI (Grant SFI 16/RC/3835)en
dc.rights© 2021, Sanjeev Kumar.en
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectWearable wristwatch antennasen
dc.subjectPIFAen
dc.subjectElectrically small antennasen
dc.subjectSub-GHzen
dc.subjectBandwidth enhancementen
dc.titleBandwidth enhanced sub-GHz wristwatch antennas for wireless body sensor network applicationsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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