Printed symmetric inverted‐F antenna with a quasi‐isotropic radiation pattern

This article presents a tag antenna with a quasi‐isotropic radiation pattern operating in the UHF band to eliminate the shadow zone in RFID systems. The proposed tag antenna has a symmetric inverted‐F structure with a bent section and is printed on a 50 μm‐thick PET substrate for easy and low‐cost fabrication. The detailed design parameters of the antenna were optimized using a Pareto genetic algorithm in conjunction with the IE3D EM simulator. The optimized antenna shows 3.2% fractional bandwidth for S11 < −10 dB, more than 87% efficiency in the operating frequency band, and less than 6 dB gain deviation. The measured reading range between the tag and reader is between 1.4 and 2.2 m.