第二篇现代天线技术.pdf

Shanghai Jiao Tong University Modern antenna theory and Technology ——Chapter 2: Basic theory Prof. Ronghong Jin Assoc. Prof. Junping Geng CMRFT, E.E. Dept., Shanghai Jiao Tong University 2009－9 9/14/2010 1 Basic theory of antenna Introduction  Maxwell equation  Basic concept:Radiation,Retarded potential (滞后位)  Electric current element  Magnetic current element (electric current loop)  Parameters 9/14/2010 2 Introduction The physical significance of Maxwell equations  Based on radiation and retarded potential, introduce the basic electric dipole and magnetic dipole  Discuss the parameters 9/14/2010 3 Basic theory of antenna Introduction Maxwell Equation  Basic concept:Radiation,Retarded potential (滞后位)  Electric current element  Magnetic current element (electric current loop)  Parameters 9/14/2010 4 Maxwell Equation  Discover the relation between the source and radiated field  Faraday’s law of induction ∂B ∇×E − 时变磁场激发时变电场 ∂t  Amp`ere ’s law as amended by Maxwell ∂D 传导电流和时变电场均 ∇×H J + ∂t 激发时变磁场 9/14/2010 5 麦克斯韦方程组与边界条件（续） 磁通连续性原理 ∇⋅B 0 穿过封闭曲面的磁通量恒