| Summary: | 碩士 === 國立臺北科技大學 === 電子工程系研究所 === 103 === In pace with the trend of smart wearable devices, the related components of the wearable devices must meet the miniaturization and low-power design requirements. Moreover, the key to enhance product effectivenss of wearable devices is the wireless communication technology such as near field communication, Bluetooth, Wi-Fi and Radio Frequency Identification (RFID) to connect smart phone. In view of this, the main purpose of this paper is to propose a design for miniaturized a novel passive RFID tag antenna which integrates a non-contact transformer between the tag antenna and chip. In other words, the inductive coupling and magnetic resonance technologies are applied rather than using the mechanical electrical connection between antenna and chip module. This will result in miniaturizing antenna size and lifting reliability for engineering structure of RFID tag, bringing about the RFID application can be integrated into smart wearable devices. Furthermore, the coupling coefficient of loosely coupled transformer is lower than traditional transformers. In order to improve wireless power transmission system efficiency, the mathematical analysis have been introduced following the derivation of equivalent model of mutual inductance and electromagnetic simulation.Through the impedance matching, the compensation capacitorscan be well implemented at each side of the coils, and Q factor will be satisfied for achieving bifurcation-free operation. Under such that conditions, the parameter design of the antenna can be accomplished. At the end, in order to verify the feasibility of the proposed method, the design was testified by the hardware circuit actual test, and the experimental results displayed in the reader output power is 26 dBm, and the tag farthest operating distance is 40mm. According to the formula of Biot-Savart Law, the 40mm corresponding optimum operating distance of side length of the antenna should be 56mm. The side length of the antenna in this paper is only 28mm long, it has validated that the proposed method in this paper is feasible.
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