As the advanced technology in the Internet of Things (IoT), ultra-high frequency radio frequency identification (UHF RFID) tag has broad application prospects and significant research value. However, the transmission performance of UHF RFID on the metal surface and embedded in metal is severely impaired, bringing new challenges to its application for long-distance reading and writing. On this basis, an embedded metal UHF RFID tag design method is proposed in this paper. A planar inverted F antenna (PIFA) structure is optimized to enhance the anti-metal performance of the tag. The embedded feed design is adopted to achieve preferable impedance matching between antenna and chip. Besides, a series of electromagnetic simulations were investigated to optimize the performance of the tag, which can ultimately achieve the maximum gain of -9.7 dB in the metal groove, with the reduced volume of 19.8 mm×25.8 mm×2 mm by employing the meandering technology and the method of adding metal via holes. Finally, when the self-made tag is embedded in the metal groove, the experimental results demonstrate that the maximum reading distance can reach 1.26 m, indicating that the tag developed in this paper has significant practical value in the case of embedded metal.
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