高频天线性能增强方法研究

Study on Performance Enhancement of High Frequency Antenna

采用有限元的方法对一选定天线的场强进行仿真分析,并结合实际测试来研究和论证的。工作频率为13.56 MHz。基于亥姆霍兹线圈磁场叠加的原理,考虑在工作天线附近增加一开路线圈,区别是线圈与工作天线不直接相连。在电磁场环境下,附加的开路线圈感应出相应的电流和磁场进而对工作天线产生影响,并且改善工作天线的阻抗,通过调整附加线圈与工作天线之间的距离来增强所需位置的场强。此方法分析了附加线圈与工作天线之间不同的位置、距离以及附加线圈的大小和通断等情况,给出了这些情况下工作天线的电流和磁场的变化。通过仿真和实测数据表明此方法的有效性。

The antenna field is simulated by finite element method with 13.56MHz operating frequency. One additional coil, which is not directly connected to the antenna, is added based on the principle of the magnetic field superposition of Helmholtz coil. In the electromagnetic field, the current and the electric field of the antenna are induced by the additional coil, which can optimize the antenna impedance. Furthermore, the electric field in the detecting position can also be enhanced by tuning the distance between the additional coil and the antenna. The value of the current and the magnetic field are analyzed with different coil positions, sizes, working states （on or off） and distances between the additional coil and the tag. The proposed method is proved by both simulation and measurement.