摘录一本大师写的讲义里的句子给大大参考: Electromagnetic field is like a chameleon—its physics changes as the frequency changes from static to optical frequencies. Electromagnetics is described by fields— a field is a function of 3D space and time. These fields satisfy their respective PDEs that govern their physics. -------------------------------------------------------- When the object size is much less than the wavelength, the physics of the field around it is dominated by the fact that the time derivative is unimportant compared to the space derivative. The field physics is close to that of static field. In the mid-frequency regime, the space derivative is equally important compared to the time derivative, but the size of the object, and hence the boundary condition, still controls the nature of the solution. In the high-frequency regime, the boundary condition plays a lesser role compared to the equations in shaping the solution. Hence, the solution resembles the homogeneous solutions of electromagnetic equations, which are plane waves. Plane waves are mathematical representation of rays, and hence, ray physics becomes more important in this regime. -INTEGRAL EQUATION METHODS FOR ELECTROMAGNETIC AND ELASTIC WAVES by Weng Cho Chew , Mei Song Tong and Bin Hu A Publication in the Morgan & Claypool Publishers series LECTURES ON COMPUTATIONAL ELECTROMAGNETICS #12 ISSN: 1932-1252 很抱歉我其实是来骗p币的XD 若有违反版规请板上大大提醒 ※ 引述《saltlake (SaltLake)》之铭言： : 射频波(radiofrequency)的行为 : 我们可以用电流的观念去模拟 : 讲得更复杂一点就是可以用拉普拉丝方程式去计算 : 而一旦频率更高到了微波领域 : 我们就必须考虑电磁波的观念 : 这时候有所谓波的近场和远场等差别 : 概念上不能再用电流的观念 : 可是 : 目前看到的书本不幸地都没有从理论方面更具体解释 : 为什麽射频波和微波这两类电磁波 : 不能都用马克士威方程式 : 从电磁波的角度去计算或了解? : 或者说 : 有没有甚麽书或文章 : 有比较清楚详尽的数学推导 : 从马克士威方程式出发 : 然後根据电磁波频率的显着不同 : 导出射频波的行为是用拉普拉斯方程式? : 谢谢 --

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