电小线圈近场分析

Near field analysis of electrically small loop

天线的近场分析在近场通信(NFC)、电磁兼容(EMC)、阵列天线设计等领域越来越受到关注。准确高效的近场分析方法对于近场的分布控制和引导机制等有着重要的作用。本文针对典型天线磁偶极子(电小线圈)的近场进行了初步的理论研究,主要分析了磁偶极子的近场平均能量密度分布、有功功率和无功功率的关系和分布。并通过磁偶极子的场分量计算平均坡印廷矢量,从而定性分析了线圈"储能"和"辐射能量"的关系,同时根据平均坡印廷矢量给出了电小线圈的近场"储能"中能量流动的物理图像。本文还计算了磁偶极子的平均电场能量密度和平均磁场能量密度,并进一步分析了二者的分布以及比较了二者的大小关系。

The near field analysis of antennas is necessary in the Near Field Communication(NFC),Electromagnetic Compatibility(EMC), array antenna design and so on. Accurate and efficient method ofnear field analysis plays an important role in the distribution control and the leading mechanism of thenear field. In view of the typical magnetic dipole antenna(electrically small loop) for near field theoryresearch, the near field energy distribution, active power(radiation power) distribution and reactivepower(non-radiation power) distribution are analyzed. The average Poynting vector could be calculatedthrough the magnetic dipole field component and then the relation between the stored energy and theradiation energy can be qualitatively analyzed. At the same time, the small electric loop near field storedenergy flow in the physical image is given. The average electric field energy density and the averagemagnetic energy density are also calculated and compared.