L W 1 g L 1 g W H S 1 C x y z 2 g L 2 g W 2 C 3 C m L m W s L s W l W 1 l L 2 l L Printed Antenna for HF- and UHF-RFID Tag Teerapol Phatarachaisakul , Tajchai Pumpoung, Pitchanun Wongsiritorn, Russamitut Pansonboon and Chuwong Phongcharoenpanich Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand E-mail: kpchuwon@kmitl.ac.th Abstract - The dual-band tag antenna designed for HF- RFID (13.56MHz) and UHF-RFID (920-925 MHz) applications along Thailand standard is proposed. The overall dimension of the tag antenna has the size of a credit card in order to implement the RFID for the highway tracking and tolls systems. The tag antenna is designed on FR-4 substrate with 0.3 mm thickness. To achieve the dual band operation, the designed tag antenna structure is based on the loop (spiral coil) and the meander-line structure with T-matching technique for HF- RFID and UHF-RFID technologies, respectively. Index Terms — Dual band RFID， HF-RFID， UHF-RFID , Tag Antenna I. INTRODUCTION The demands of Radio Frequency Identification (RFID) systems have been rapidly growth in both the business world and daily life [1-2]. In general, the RFID system is used in many applications such as retail store, logistics, people identification, animals products and many others. Due to the growing of RFID technology, the tag antenna design becomes one of the interesting research topics. The RFID technologies are generally distinguished into four frequency ranges; i.e., low frequency (125-134.2 kHz), high frequency (13.56 MHz), ultra high frequency (433, 860-960 MHz) and microwave frequency (2.45, 5 GHz). Furthermore, the UHF operating frequency band is different in each region and the operating frequency band of Thailand is from 920 MHz to 925 MHz This paper presents the tag antenna designed for dual band RFID [3-4] applications. The HF-RFID tag antenna is constructed using the loop antenna [5] (spiral coil) and the turn of the loop is used as the matching structure. To design the UHF-RFID tag, the meander-line structure [6] is use to increase the electrical length. The proposed dual-band antenna can be applied for both long range communications (UHF band) and short range communications (HF band) in a single antenna. II. TAG ANTENNA STRUCTURE The tag antenna configuration is presented in Fig. 1. The photograph of the prototype antenna is shown in Fig. 2. The HF antenna parameters are L = 84 mm, W = 54 mm, C 1 = 0.5 mm, H = 10 mm and S = 1 mm. The UHF antenna parameters are W l = 40 mm, L l1 = 40 mm, L s = 18 mm, W s = 18 mm, L m = 17 mm, W m = 12 mm, C 2 = 1 mm and C 3 = 2 mm. The dimension of the feeding ports are L g1 = 0.985 mm and W g1 = 0.794 mm for HF-RFID antenna and L g2 = 4 mm and W g2 = 4 mm for UHF-RFID antenna. The antenna is designed on the FR4 substrate (ε r =4.3 and height = 0.3 mm) with copper thickness of 0.05 mm. The HF tag antenna is connected to SIC5600 IC chip [7] with the capacitor of 23.5 pF at 13.56 MHz and the UHF tag antenna is connected to NXP G2XL IC chip [8] with the impedance of 15.88 - j148.82 Ω at the 922.5 MHz. Fig. 1. The proposed tag antenna structure. Fig. 2. The photograph of the tag antenna. III. SIMULATED AND MEASURED RESULTS A. HF-RFID Tag Antenna The simulated inductance of the proposed HF tag antenna is 6.134 μH and the measured inductance is 3.143 μH. B. UHF-RFID Tag Antenna 1. Reflection The reflection coefficient or |S 11 | (dB) of the proposed tag antenna is illustrated in Fig. 3. It is obvious that the simulated and measured |S 11 | (dB) are less than -10 dB covering the frequency range from 919.72 to 925.12 MHz FR2B_10 FR2B_10 FR2B_10 FR2B_10 Proceedings of ISAP 2014, Kaohsiung, Taiwan, Dec. 2-5, 2014 513