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A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 mm-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S 11 < À10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170-240 cm for an arbitrary rotation angle of the tag.

This letter presents a wideband quasi‐Yagi antenna fed by a microstrip‐to‐slotline transition. The transition consists of a microstrip radial stub and slot radial stub, both at 90° but with different radii, to achieve wideband impedance matching. The antenna has a measured fractional bandwidth of approximately 46% (4.64–7.42 GHz) for a −10 dB reflection coefficient and a flat gain of 6.0–6.75 dBi with a front‐to‐back ratio and cross‐polarization level better than 17 and −15 dB, respectively, across the bandwidth. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:150–153, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26504

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