面向汽车进入的NFC天线设计
NFC Antenna Design for Automobile Entry

为了使得用户更加便捷的开启车门，本文面向汽车进入系统，基于NFC技术和原理设计了一种置于门把手环境下的NFC天线。利用HFSS软件完成了NFC天线的模型设计，仿真分析了天线面积、走线宽度、走线间距和介质板厚度对天线等效电感值的影响，结果表明，较大的线圈面积、较小的走线宽度和走线间距可以有效地提高天线的等效电感值，而介质板的厚度对等效电感值影响较小，需根据仿真值进行选择。随后基于Smith原图工具完成了天线电路的阻抗匹配设计，将计算出的匹配参数值带回到模型中进行仿真，对匹配后天线的回波损耗、电压驻波比进行了评价。从结果得知本次所设计的NFC天线匹配程度高、反射损耗较小，具有良好的性能。
In order to make the user more convenient to lock the automobile, this paper designs an NFC antenna based on NFC technology and principle for the automobile entry system under the door handle environment. HFSS software is used to complete the model design of the NFC antenna, and the effects of antenna area, wire width, wire spacing, and dielectric plate thickness on the antenna equivalent inductance value are simulated and analyzed. The results show that a larger coil area, smaller wire width and wire spacing can effectively improve the antenna equivalent inductance value, while the thickness of the dielectric plate has little effect on the equivalent inductance value. The selection should be based on the simulation value. Then the impedance-matching design of the antenna circuit is completed based on the Smith tool. The calculated matching parameters are brought back to the model for simulation, and the return loss and voltage standing wave ratio of the antenna after matching are evaluated. The results show that the NFC antenna designed in this paper has a high matching degree, low reflection loss and good performance.