| The antenna theories are mainly based on study of far field, but with the development of the network and communication technology today, the short-range radio communication technologies are becoming more and more focused, and their applications are becoming wider and wider. For example, both the EAS(Electronic Article Surveillance) system and the RFID(Radio Frequency Identification) system need high effective the short-range radio communication antenna. The NFC(Near Field Communication) technology raised in these years even developed new world of short-range radio communication antenna research.This paper studied the design principle and impedance measurement method of RFID(15693 standard) antenna. The effects of different parameters on the antenna performance are analyzed in the paper. The paper also designed and stimulated a matching circuit of the antenna. During the test process, an improved scheme was proposed. In the new design, several fixed test points on a transmission line are chosen instead of previously frequency scanning. We have composed an automatic test system. The measurement results show that this method is simple and easy for antenna impedance measurements without expensive special measuring instruments. Finally, the paper analyzed the measurement results, the reasons why the errors appeared in this method, and the corresponding measures were discussed. |
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