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oai:www.ideals.illinois.edu:2142/98335 2023-07-11 col_2142_8888 col_2142_5131 com_2142_8887 com_2142_234 com_2142_5130

Jin, Jianming Jin, Jianming Bernhard, Jennifer Schutt-Ainé, José Gong, Songbin Zeng, Yunjia 2017-09-29T17:56:26Z 2017-09-29T17:56:26Z 2017-07-09 2017-08 In this dissertation, the one- and two-dimensional periodic structures are modelled and adopted in the design of near-field antennas. First, the discontinuous Galerkin time-domain (DGTD) method is applied to model the scattering from periodic structures. The modelling of dispersive media is incorporated into a three-dimensional DGTD scheme, which is capable of studying plasmonic periodic structures at optical frequencies. Various numerical examples are presented to demonstrate the applications of the proposed algorithm. Second, a new methodology for modelling and characterization of one-dimensional periodic structures with nonstraight geometries is developed. The one-dimensional zero-phase-shift line (ZPSL) is analyzed to obtain its dispersion characteristics. Equivalent circuit models are proposed to characterize the ZPSL structures. A design guideline is developed and demonstrated to enlarge the interrogation zone of a ZPSL loop antenna for near-field wireless systems. Third, the full dispersion characteristics, including phase and attenuation constants, of the ZPSL are analyzed in a loop configuration. Based on the dispersion characteristics, a periodic ZPSL loop antenna with uniformly distributed unit cells is studied, and a nonperiodic ZPSL loop antenna with nonuniformly arranged unit cells is designed for an improved near-field performance. Fourth, a low-profile directional ZPSL loop antenna is proposed by placing an artificial magnetic conductor (AMC) reflector behind a ZPSL grid-loop antenna. The grid-loop configuration is designed such that an enhanced magnetic field distribution can be realized on the electrically large ZPSL loop antenna with a simple feeding network. The AMC reflector with four-arm spiral unit cells is included to achieve a directional field distribution as well as to further increase the magnetic field intensity. Fifth, two low-profile ZPSL loop antennas are proposed to achieve a directional magnetic near-field distribution. The current distributions on the antennas are studied to realize the desired near-field pattern. Besides the directional distribution, both the antennas exhibit enhanced magnetic field intensities in the forward direction. All of the antennas are exemplified as a reader antenna for ultra-high frequency (UHF) near-field radio frequency identification (RFID) systems. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-09-29 without embargo terms The student, Yunjia Zeng, accepted the attached license on 2017-07-05 at 20:56. The student, Yunjia Zeng, submitted this Dissertation for approval on 2017-07-05 at 21:14. This Dissertation was approved for publication on 2017-07-09 at 14:02. DSpace SAF Submission Ingestion Package generated from Vireo submission #11319 on 2017-09-29 at 11:28:00 Made available in DSpace on 2017-09-29T17:56:26Z (GMT). No. of bitstreams: 3 ZENG-DISSERTATION-2017.pdf: 3626070 bytes, checksum: 2726a97b2ebd4676f66a6ab83a753800 (MD5) LICENSE.txt: 4208 bytes, checksum: b803ea91cfba7be7707f5a666b500f9c (MD5) PROQUEST_LICENSE.txt: 4554 bytes, checksum: f61feba4da3be60dca2e6b1dbd4ad388 (MD5) Previous issue date: 2017-07-09 application/pdf http://hdl.handle.net/2142/98335 en Copyright 2017 Yunjia Zeng Numerical method Periodic structures Near field Magnetic field Dispersion analysis Equivalent circuit Loop antenna Artificial magnetic conductor Radio frequency identification Ultrahigh frequency Directional antenna Antenna array Parasitic array Modeling and design of near-field antennas with periodic structures text text Electrical & Computer Eng Electrical & Computer Engr University of Illinois at Urbana-Champaign Dissertation Ph.D.