Summary
International Symposium on Antennas and Propagation
2010
Session Number:4FA1
Session:
Number:4FA1-2
A Miniatured UHF RFID Tag Antenna with Double Loop Structure
Kittima Lertsakwimarn, Chuwong Phongcharoenpanich, Kraison Aunchaleevarapan,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
Radio frequency identification (RFID) is a technology used ever more widely for identification in many applications such as in warehousing, retail, transportation, manufacturing especially supply chain systems[1]. RFID technology is used for supply chain for the purpose of tracking products and checking samples, such as labeling RFID at the cans and each can has the code. The code in RFID labeling indicates the product description. Therefore, the count and verification of the product can be sent to various locations that can quickly and easily operate, RFID system can be used in the different frequency bands. One frequency band becoming a standard for supply chain management is the ultra-high-frequency (UHF) band. The operating range of UHF band is further than the LF- and HF-RFID systems. The LF- and HF-RFID systems use the nearfield coupling techniques whereas the UHF-RFID utilizes the far-field radiation technique. The UHF frequency band in different countries have different frequency ranges allocated for RFID application such as 865-868 MHz in Europe, 902-928 MHz in North and South Americas, 950-956 MHz in Japan and some Asian countries whereas Thailand used 920-925 MHz[2]. The typical system operation consists of tag, reader and information management system. The reader uses an antenna to transmit radio energy to interrogate a transponder or tag that is attached to the item to be identified. RFID tags are directly attached to objects. In supply chain system, objects can be made of different materials such as cardboard, glass, plastic, wood and others. The antenna parameters such as input impedance and radiation pattern will be changed that is affected from material. Especially, when the RFID tags are placed near objects with high conductivity, the performance of RFID tag is dramatically degraded[3]-[4]. The different approaches have been presented in the literature to overcome this problem. The inverted-F antenna (IFA)[5], planar inverted-F antenna (PIFA)[6], and patch-type antenna structures[7] are specifically antennas for identification of metallic objects. Their performances still considerably depend on the condition of the supporting metallic objects such as conductivity, size and shape[8]. Mainly, the sizes of these antennas are very large and very thick. The large size and thickness of tag antenna may restrain the use of RFID from certain practical application as the bar code with this structure to accompany the products that is the metallic material. In this case, the thickness of the packaged RFID metal tag needs to be less than 1.5 mm, where this size is similar to the barcode. This paper presents a miniatured RFID tag antenna design for metallic material. The allocated UHF band in Thailand is 920?925 MHz. The simulation and experimental results of the antenna characteristics is presented.