Antenna characterization using phaseless near-field antenna measurements

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dc.contributor.authorBrown, Trevor
dc.contributor.examiningcommitteeBridges, Gregory (Electrical and Computer Engineering) Fiege, Jason (Physics and Astronomy)en_US
dc.contributor.supervisorMojabi, Puyan (Electrical and Computer Engineering) Jeffrey, Ian (Electrical and Computer Engineering)en_US
dc.date.accessioned2016-09-12T21:43:40Z
dc.date.available2016-09-12T21:43:40Z
dc.date.issued2016
dc.degree.disciplineElectrical and Computer Engineeringen_US
dc.degree.levelMaster of Science (M.Sc.)en_US
dc.description.abstractThis thesis focuses on the application of electromagnetic inverse source techniques to characterize antennas using phaseless (amplitude-only) near-field (NF) measurement data. Removing the need to measure phase reduces the overall cost of the measurement apparatus since simple power meters can be used instead of expensive vector network analyzers. It has also been shown in the literature that a phaseless approach can improve the accuracy of the calculated far-field (FF) pattern in the presence of probe positioning errors compared to the amplitude-and-phase approach. A brief discussion on the state-of-the-art methods for characterizing antennas using phaseless near-field measurement data is presented. Two general approaches used most often to perform near-field to far-field (NF-FF) transformations, namely modal expansion and source reconstruction, are explained in detail for scenarios with and without phase information. A phaseless source reconstruction method (SRM) is the primary focus of this work. The SRM is an application of an electromagnetic inverse source technique and therefore, the complexities of solving the associated ill-posed inverse source problem are discussed. The application of the SRM to spherical and planar measurement geometries are presented along with the concerns regarding regularization resulting from discretizing the ill-posed system. A multiplicative regularization (MR) scheme originally developed for inverse scattering is adapted to suit the nonlinear cost functional for the phaseless planar measurement case and the mathematical framework is derived in detail. The resulting MR-SRM is fully automated and incorporates adaptive regularization. The developed algorithms are evaluated using several examples with synthetic phaseless NF data demonstrating the benefits and limitations of the source reconstruction method and the multiplicative regularization scheme. The application of the SRM to antenna diagnostics using phaseless NF data is also shown. Finally, the developed planar algorithms are tested with experimentally collected phaseless measurement data to demonstrate their potential as suitable antenna characterization techniques that can be of interest to the antenna measurement community.en_US
dc.description.noteOctober 2016en_US
dc.identifier.urihttp://hdl.handle.net/1993/31693
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectPhaseless measurementsen_US
dc.subjectInverse problemsen_US
dc.subjectAntenna measurementsen_US
dc.subjectOptimization methodsen_US
dc.subjectSource reconstruction methoden_US
dc.subjectNear-field to far-field transformationen_US
dc.titleAntenna characterization using phaseless near-field antenna measurementsen_US
dc.typemaster thesisen_US
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