Envelope-tracking integral equation methods for band-pass transient scattering analysis

dc.contributor.advisorYilmaz, Ali E.
dc.contributor.committeeMemberLing, Hao
dc.contributor.committeeMemberAlu, Andrea
dc.contributor.committeeMemberDemkowicz, Leszek
dc.contributor.committeeMemberSchulz, Karl
dc.creatorKaur, Guneet
dc.date.accessioned2018-01-23T21:22:02Z
dc.date.available2018-01-23T21:22:02Z
dc.date.created2015-12
dc.date.issued2015-09-28
dc.date.submittedDecember 2015
dc.date.updated2018-01-23T21:22:03Z
dc.description.abstractThis dissertation presents envelope-tracking (ET) integral equation methods to efficiently analyze band-pass scattering problems. Unlike the traditional time-domain marching-on-in-time (TD-MOT) schemes, ET-MOT schemes solve for space-time samples of not the current density but its complex envelope. The time step size used in ET-MOT schemes is inversely proportional to the bandwidth of the fields of interest and not their maximum frequency content; thus, ET-MOT schemes can use (much) larger time step sizes for band-pass analysis: the smaller the bandwidth of the fields compared to their maximum frequency content, the larger the time step size in ET-MOT solutions compared to those in the TD-MOT solutions. Despite the reduction in the number of time steps, ET-MOT schemes suffer from high computational costs that also affect time- and frequency-domain integral equation methods. This dissertation presents an FFT-based algorithm, the ET adaptive integral method (ET-AIM), to reduce the computational complexity of ET-MOT schemes. ET-AIM is both theoretically and empirically compared to its time-domain and frequency-domain counterparts, TD-AIM and FD-AIM, respectively. Because the performance of the envelope-tracking methods is a complex function of the bandwidth of interest and because each method has different accuracy-efficiency tradeoff, only limited deductions can be made from theoretical comparison of the methods. Thus, in addition to theoretical comparisons, an empirical approach for comparing the different methods is presented: To perform a fair, meaningful, and generalizable comparison, benchmark problems are identified, an appropriate error norm is defined, and the key parameters of the methods are optimized subject to a constraint on the error norm. Computational costs are measured and compared for all three methods for solving progressively larger benchmark scattering problems for varying frequency bandwidths. This dissertation also proposes an out-of-core algorithm to ameliorate the high memory requirement of FFT-accelerated time-marching methods. The proposed algorithm exchanges the core memory requirement with external storage space requirement without significantly increasing the simulation time. The performance of the proposed methods is demonstrated by solving surface- and volume-integral equations pertinent to scattering problems that involve good conductors and inhomogeneous volumes with complex dielectric properties. For example, numerical results obtained using ET-AIM are presented for analysis of scattering of radar pulses from a PEC missile, a generic aircraft, etc. and antenna radiation near anatomically realistic human body model.
dc.description.departmentElectrical and Computer Engineering
dc.format.mimetypeapplication/pdf
dc.identifierdoi:10.15781/T24Q7R64X
dc.identifier.urihttp://hdl.handle.net/2152/63180
dc.language.isoen
dc.subjectEnvelope-tracking
dc.subjectElectromagnetics
dc.subjectIntegral equations
dc.subjectBand-pass analysis
dc.titleEnvelope-tracking integral equation methods for band-pass transient scattering analysis
dc.typeThesis
dc.type.materialtext
thesis.degree.departmentElectrical and Computer Engineering
thesis.degree.disciplineElectrical and Computer Engineering
thesis.degree.grantorThe University of Texas at Austin
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy
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