标题： 经典电动力学互易定理的新视角 显示英文标题

标题： New Perspective on the Reciprocity Theorem of Classical Electrodynamics

摘要： 我们提供了一个简单的物理证明，说明经典电动力学中的互易定理在包含线性极化和线性磁化物质的材料介质的一般情况下成立。 激励源被取为点偶极子，可以是电偶极子或磁偶极子，观测点处监测的场可以是电场或磁场，无论激励偶极子的性质如何。 材料系统的电和磁极化率张量可以在空间中各点不同，但它们不能是时间的函数。 在非色散介质的情况下，局部极化率张量的唯一其他约束是在每一点上都是对称的。 该证明可以很容易地扩展到具有空间色散的介质：为了互易性成立，将位置r_m处的电偶极子复数值大小与r_n处电场强度相关联的电极化率张量Chi_E_mn必须是Chi_E_nm的转置。 同样，磁极化率张量的必要且充分条件是Chi_M_mn = Chi^T_M_nm。 显示英文摘要

摘要： We provide a simple physical proof of the reciprocity theorem of classical electrodynamics in the general case of material media that contain linearly polarizable as well as linearly magnetizable substances. The excitation source is taken to be a point-dipole, either electric or magnetic, and the monitored field at the observation point can be electric or magnetic, regardless of the nature of the source dipole. The electric and magnetic susceptibility tensors of the material system may vary from point to point in space, but they cannot be functions of time. In the case of spatially non-dispersive media, the only other constraint on the local susceptibility tensors is that they be symmetric at each and every point. The proof is readily extended to media that exhibit spatial dispersion: For reciprocity to hold, the electric susceptibility tensor Chi_E_mn that relates the complex-valued magnitude of the electric dipole at location r_m to the strength of the electric field at r_n must be the transpose of Chi_E_nm. Similarly, the necessary and sufficient condition for the magnetic susceptibility tensor is Chi_M_mn = Chi^T_M_nm.