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| With the development of Radio Frequency Identification (RFID), it has been widely used in many fields, such as transportation, shopping malls and logistics. Among them, RFID tag antenna is an important part of this technology, and the performance of tag antenna is also concerned by more and more people. It has been noticed that different working environments have a great impact on the performance of tags. Especially on the metal surface, because the metal will reflect a lot of electromagnetic waves, the performance of ordinary tag antenna may deteriorate dramatically, resulting in the inability to effectively read information. The goal of this project is to design a RFID tag antenna suitable for free space and metal surface and test its performance. An RFID tag is designed for ultra-high frequency band (902MHz-928MHz) in North America. The tag antenna is based on the structure of micro strip antenna. The tag antenna model is designed and simulated by using three-dimensional electromagnetic simulation software. The whole model consists of surface metal patch, medium substrate and metal floor at the bottom. In terms of bandwidth, a vertical H-slot method is used to cut the current path of the original patch to form multiple resonant modes, which expands the bandwidth of the antenna. The impedance of Impinj\'s Monza-4 chip is 11-143j at 915MHz. After testing, the echo loss of the tag antenna S11 is less than - 10dB in the range of 902MHz-928MHz. The gain of this antenna is also good. After the simulation and optimization process, the tag antenna is fabricated, the antenna object is made and the reading distance of the antenna is measured in free space and metal surface. |
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| Keywords:Electronic Science, anti-metal, impedance matching, RFID, tag antenna, bandwidth |
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