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Author: search.filters.author.Phaebua, KittisakSubject: search.filters.subject.UTD

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    Radiation analysis of an equivalent magnetic UHF-RFID tag located on a coated metallic sphere using UTD method
    (2017-01-17)
    Phaebua, Kittisak
    ;
    Wongsiritorna, Pitchanun
    ;
    Lertwiriyaprapa, Titipong
    ;
    Phongcharoenpanicha, Chuwong
    The radiation analysis of an equivalent magnetic UHF-RFID tag antenna located on a coated metallic sphere using UTD method is illustrated in this work. The conventional UHF-RFID tag can be represented by electric current source and is designed by employing the dipole antenna concept. The electromagnetic (EM) radiation characteristic of UHF-RFID tag mounted on the metallic and material coated metallic curved objects can be distorted because the electric field is parallel to the metallic surface. It is very important to include the metallic objects when designing the UHF-RFID tag. In this work, the uniform geometrical theory of diffraction (UTD) method is employed to predict the EM radiation characteristic of the electric current source and equivalent magnetic current sources mounted on a coated metallic sphere. It is noted that the equivalent magnetic current source provides broader beamwidth. This makes the communication area wider than the electric current source case. An example of UHF-RFID tag is designed in this work based on the equivalent magnetic current source or slotted antenna concept. The calculated result is confirmed by comparing with the CST Microwave studio simulation. It is confirmed that the UTD method is suitable for the radiation calculation of the tag mounted on material coated metallic curved objects.
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    Modified UTD-based UHF RFID tag antenna with two-pronged fork slot for coated metallic cylindrical surface
    (2016-04-12)
    Wongsiritorn, Pitchanun
    ;
    Phongcharoenpanich, Chuwong
    ;
    Pumpoung, Tajchai
    ;
    Phaebua, Kittisak
    ;
    Lertwiriyaprapa, Titipong
    Abstract: This research has proposed a modified uniform geometrical theory of diffraction (UTD) for radiation to investigate the radiation pattern on the coated metallic curved surface. The modified UTD, which accounts for the existence of the impedance surface (coating), is applied to the development of a compact UHF RFID passive tag antenna with a two-pronged fork slot to be mounted on the coated metallic cylindrical drum. In the calculation, the UHF RFID tag was initially represented by electric tangential (E<inf>z</inf>-source) and equivalent magnetic tangential to the surface (M<inf>z</inf>-source). The results indicated that the M<inf>z</inf>-source could achieve a greater communication area, and thus the design of the tag antenna is of equivalent magnetic source. Simulations were then carried out to determine the optimal antenna parameters, and an antenna prototype was fabricated and tested. The simulation and measured results are in agreement. The research findings validate the effectiveness of the modified UTD-based UHF RFID tag for application on the coated metallic curved surface.