The measured gain performance is shown in Figure 11 at eight different frequencies up to 10 GHz and demonstrates a variation similar to other wideband antennas. 4. CONCLUSIONS In this article, a novel compact PMA has been proposed for future UWB handset applications. The fabricated antenna satis- fies the 10-dB return loss requirement from 3.12 to 10.63 GHz. The feedgap distance, the sizes of slot and sleeve on the radiat- ing patch and ground plane to obtain the wide bandwidth have been optimized by parametric analysis. A parametric study was done that wideband characteristics can be achieved for the small antenna with appropriate choice of parameter. The proposed antenna has a simple configuration and is easy to fabricate. Ex- perimental results show that the proposed antenna could be a good candidate for UWB application. ACKNOWLEDGMENTS The authors thank Microwave Technology Company staff for their beneficial and professional help. REFERENCES 1. H. 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Kong, Electromagnetic wave theory, EMW Publishing, Cam- bridge, 2000. 15. A.A. Eldek, A small ultra wideband planar tap monopole antenna with slit, tapered transition and notched ground plane, Microwave Opt Technol Lett 48 (2006), 1650–1654. 16. Ansoft High Frequency Structure Simulation (HFSS), Ver. 10, Ansoft Corporation, 2005. 17. J.P. Lee, S.O. Park, and S.K. Lee, Bow-tie wideband monopole antenna with the novel impedance-matching technique, Microwave Opt Technol Lett 33 (2002), 448–452. V C 2010 Wiley Periodicals, Inc. PLANAR ANTENNAS FOR PASSIVE UHF RFID TAGS ON FLEXIBLE COPPER CLAD LAMINATE Arun Kumar, 1 Davinder Parkash, 1 and M. V. Kartikeyan 2 1 Department of ECE, HCTM, Kaithal, Haryana 136 027, India; Corresponding author: arun_ktl@yahoo.co.in 2 Department of Electronics and Computer Engineering, IIT Roorkee, Uttarakhand 247 667, India Received 25 October 2009 ABSTRACT: In this article, planar antenna designs for passive RFID tags for ETSI and FCC band are discussed. Performance of designs is evaluated by monitoring conjugate match factor and radiation efficiency. The proposed antenna designs were fabricated on a flexible copper clad laminate of thickness 5 mil, and the read range of proposed tags were measured. V C 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1761–1763, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25329 Key words: RFID; planar antenna; UHF antennas 1. INTRODUCTION Radio frequency identification (RFID) is a rapidly developing automatic identification method, which uses RF signals for stor- ing and remotely retrieving data using RFID tags. Use of RFID technology can be seen in various areas such as toll collection, asset identification and tracking, retail item management, access control, animal tracking, e—document, and vehicle security. Major hardware components of a RFID system are reader/ interrogator, reader antenna, and a RFID tag/transponder. Pas- sive RFID tags do not have any internal source of energy. They are composed of an electronic Integrated Circuit (IC) that usu- ally contains data and an antenna. The IC is powered by the electromagnetic waves radiated by the reader that also commu- nicates with the tag to get its data [1]. Communication in passive UHF RFID systems is based on backscattering of modulated electromagnetic wave: reader transmits energy and commands to Figure 11 Measured peak antenna gain for the proposed antenna DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 52, No. 8, August 2010 1761