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Design of RFID antennas in metal environment with broad circular polarization bandwidth

In this thesis, we propose tag and reader antennas which are suitable when
attended to metal material for Radio Frequency Identification (RFID) systems. For tag
antenna design, we use microstrip antenna with ground plane to reduce the metal
effect. In order to match the impedance of different IC chip, some parameter of the tag
antenna are designed and described, which can be used to adjust the impedance of tag
antenna. For reader antenna design, circularly polarized patch antenna can be
achieved by using dual-feeding technique with U-shaped aperture-coupled, where the
dual feeds with a phase shift and equal input power amplitude are provided by a
Wilkinson power divider. Therefore, a good right-hand circular polarization is
obtained and a 3-dB CP bandwidth of the designed reader antenna is greater than 30
¢H.
900
We then design dual-band antenna and broad CP bandwidth antennas. In the
dual-band design, two resonant paths are utilized to cover 915 and 2450 MHz bands
that can be used for RFID systems in UHF and ISM bands. In the broad CP bandwidth
design, a square slot antenna is used with a cross patch placed at the center of the
square slot. Two orthogonal resonant modes with phase difference and equal
input power amplitude can be excited by choosing the proper dimensions of the cross
patch. A 3-dB CP bandwidth of the designed circularly polarized antenna is greater
than 12¢H.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0620106-142203
Date20 June 2006
CreatorsChou, Chien-Chang
ContributorsChih-Wen Kuo, Tzyy-Sheng Horng, Ken-Huang Lin
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0620106-142203
Rightsnot_available, Copyright information available at source archive

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