电子信息与通信工程专业英语lesson41(太原理工大学版).pptVIP

《通信与信息工程专业英语教程》 Outline 4.1 Electromagnetic Fields Theory 4.2 Antenna 4.1 Electromagnetic Fields Theory Outline Maxwell’s equations Current continuity equation Constitutive relations Boundary conditions Power and energy Terminology vector n. [数]向量, 矢量, 带菌者 vt.无线电导引 scalar n. 数量,标量 adj. 分等级的,数量的,标量的 position vector n. 位矢, 方位向量, 位置矢量 flux n. [物]流量, 通量, 涨潮, 变迁 vi.熔化, 流出 vt.使熔融, 用焊剂处理 contour n.轮廓, 周线, 等高线 emf abbr. 电动势 (electromotive force) Stockes’ theorem n. 斯托克斯定理 divergence theorem n. 散度定理 conduction current n. 传导电流 displacement current n. 位移电流 solenoidal fields n. 螺线管磁场, 管形场 continuity equation n. 连续性方程 constitutive relation n. 本构关系 isotropic adj.等方向性的,各向同性的 dielectric constant n. 介电常数 relative permeability n. 相对磁导率 conductivity n.传导性, 传导率 anisotropic adj.各向异性的 tensor n. 张量, 张肌 Text tour In1864, James Clerk Maxwell proposed one of the most successful theories in the history of science. In a famous memoir to the Royal Society, he presented nine equations summarizing all known laws on electricity and magnetism. By postulating the need for an additional term to make the set of equations self-consistent, Maxwell was able to put forth what is still considered a complete theory of macroscopic electromagnetism. To form a complete field theory we need a source field, a mediating field, and a set of field differential equations. This allows us to mathematically describe the relationship between effect (the mediating field) and cause (the source field). In Maxwell’s equations, the source field consists of the vector field (the current density) and the scalar field (the charge density), the mediating field is the electromagnetic field consisting of the set of four vector fields , , and . =electric field intensity (vector), volts/meter (V/m) =magnetic field i