| With the constant development of wireless communication, RFID technology has been widely used in all kinds of specific application areas. Radio Frequency Identification, is a non-contact automatic identification technology. It transmits data by using wireless electronic magnetic wave which uses low-frequency, high-frequency, ultra-frequency, microwave etc under different conditions, taking the advantages of them, accomplishing the mission of rapid data-collection. Moreover, as it is dirty-resistible and reusable, RFID technology is seen to be more and more popular.Firstly, the dissertation studies RFID technology, including standards and classifications, and meanwhile, the technical specifications and investigating status of antenna in RFID system are analyzed and discussed. And then, this dissertation makes a research on the analysis and design of fractal antennas and bending antennas. By the means of theoretical analysis, numerical simulation and experimental verification, several novel antennas are designed, which can work at 915MHz and 2.35GHz. The author's contributions in this thesis include following aspects:(1) Based on studying the theory of fractal antennas, a fractal antenna that is compact, small, and stability performance is designed. Then, according to the actual situation, a coaxial feed microstrip fractal antenna is designed, and the simulation results show that a better impedance matching is achieved, the gain is also improved. The physical antenna tests results show that the return loss has been improved.(2) Using special bending lines can effectively expand the size of the antenna equivalent circuit, in the case of the same electrical length, bend line and the ordinary dipole current can produce the same effect, which can effectively reduce the physical size of the antenna. Based on special bending line research and analysis, a compact low profile double inverted F antenna structure, a slot coupled bending antenna structure, a coaxial feed bending antenna structure and an omni-directional antenna structure are designed.(3) Slot coupled is relatively special feed antenna, a detailed analysis of electromagnetic coupling slot antenna feed technology, on the basis, an slot tag antenna is designed, and then simulate by HFSS, the simulation results are obtained, then, analysis and research the impact of the performance of the antenna on the slot length and the Medium plate thickness. |
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