NiCuZn铁氧体磁片在NFC天线中的应用及仿真分析

Application and simulation analysis of NiCuZn ferrite flexible sheets to the NFC antenna

采用线圈式结构设计了近场通信(NFC)天线,并将NiCuZn铁氧体柔性磁片应用于NFC天线系统。利用HFSS仿真软件,研究了天线介质基板厚度、线圈走线宽度、铜线间距以及柔性磁片等对天线回波损耗、谐振频率以及磁场分布的影响。结果表明,天线的走线宽度、走线间距、介质板厚度等参数会影响天线的输入阻抗从而改变谐振频率,最佳的基板厚度0.8 mm、走线宽度a=0.5 mm、走线间距b=1 mm;金属片会导致NFC天线谐振频率偏移,而NiCuZn铁氧体柔性磁片能有效防止金属对天线磁场的干扰以及谐振频率偏移。

Flexible magnetic sheets of NiCuZn ferrite have been applied in the near field communication （NFC） antenna with coil transmission line structure. Based on the simulation with HFSS software, effects of the thickness of dielectric substrate, width of transmission line, space between adjacent transmission lines and flexible magnetic sheets on the return loss S11, resonance frequency and distribution of magnetic field have been investigated. The results show that, the input impedance of the antenna, which could be affected by the width of the transmission line, the space between adjacent transmission lines and the thickness of the dielectric substrate, would contribute to the shifting of resonance frequency, thus, the optimized three parameters are 0.8 mm, 0.5 mm, and 1 mm, respectively. In addition, the metal sheet would cause shifting of the resonance frequency of the antenna via disturbing the distribution of the magnetic field, fortunately, which can be prevent by the application of flexible magnetic sheets of NiCuZn ferrite in the antenna.