电磁场与电磁波课程绪论.ppt

1、1,Electromagnetic field and Electromagnetic waves,Lecturer： Email： Class hours：,2,Introduction,1.what this course is about and the main content 2.the development of EM theory & EM technology 3.the practical works and applications of EM 4.Assessment methods and module aims,3,A branch of physic， focus

2、 mainly on： macroscopical field theory & microscopic quantum electrodynamics,main research field of EM,theoretical basis of radio-technology， focus mainly on: research of three important application problems,1.what this course is about and the main content,4,Three important application problems: EM

3、field（or EM wave）, a form of energy，is the most important energy in the world. This field of research involves generating, storage, transforming, transmissing and comprehensive utilization of EM energy, EM wave, the carrier of information transmission, is becoming the main method to transmit&receive

4、 information for the human society. This main research field is focusing on generating, capturing, exchanging, transmissing, storing, reconstructing and comprehensive utilizing information., EM wave, an important method of detecting the unknown worlds, focuses mainly on interreactions between the re

5、search target and EM wave, capturing and reconstructing target characteristics, detecting new techniques.,5,the main content of the module: 1). Vector and vector operation. (mathematical foundation) 2). Electrostatic field. (electrostatic charge, constant current) Coulombs Law, 3).magnetic field of

6、constant current. (constant current) oersteds Law, 4). Time-Harmonic EM Field and EM wave. (time-varying) Faradays Law, interaction of time-varying E & M, Maxwells equations 5). Transmission line. coaxial-line ( oscilloscope ) 6).Waveguide. rectangular waveguide 7). Radiation and reception of EM wav

7、e antenna,6,Teaching materials: 1.杨如贵(译著)，Robert R.G. (原著），Electromagnetic fields and waves, 高等教育出版社 2.Lecture sheet Reference materials: 1.郭辉萍，电磁场与电磁波，西安电子科技大学 2.Kraus and Fleisch, Electromagnetics (with Applications), McGraw-Hill,7,2.the development of EM theory,Contribution of Coulomb（库伦）（Coulomb

8、s Law 1785） End of 18th century, German philosopher Scheling（谢林）: The universe is energetic, not unchangeable and dead. electricity is the vigor and soul of the universe. Electricity, magnet, light and heat correlate to one another. Oersted(奥斯特）, believer of Scheling, started to research on the rela

9、tionship between electricity and magnet from 1807.He found that the force of electric current acted on Magnetic needles, at1820.,8,Ampere（安培） found that the direction of the force be perpendicular to the current direction and the direction of current wires vertical line. Mathematical formula (Ampere

10、s theorem) Under the influence of Scheling and Oersted , Faraday （法拉第）believed that electricity, magnet, light and heat correlated to one another. And he was keenly aware that electricity can act on magnet, and vice versa. From 1821, he started working on the experiment of magnet generating electric

11、ity. At 1831, he found that when the bar magnet was inserted into the conductor coil, current was generated in the coil. This shows that there is a close interaction between electricity and magnet.,9,Maxwell （麦克斯韦）developed the concept of field. On the basis of Faradays experiment, he summarized the

12、 rules of electromagnet phenomenon and introduced the concept of displacement current. The core concept is that changing electric field can generate magnetic field and changing magnetic field can generate electric field. Maxwells equations: partial differential equations, integral equations classica

13、l electromagnetic theory,10, At 1887, German scientist, Hertz（赫兹）,verified Maxwells prediction of EM wave. radiotelegram An epoch in the theory and applicaton of EM field Important subject,11,Radiotelegram:(mark the start of EM waves application) 1895, Marconi, Italian,the transmittion distance :2.5

14、 km. 1896，Popov, 250meter, 1899, English Channel,31miles(1 mile=1609 meters) 1901，Atlantic, 3200km 1909,Marconi, Nobel Prize in Physics wire telephone: 1876,A.G.Bell,100th anniversary in America, popularized,3.the practical works and applications of EM,12,Broadcast: 1906，Fessenden（费森登 ）, American, 5

15、0KHz(transmitter)，Antenna, Boston to a ship in Atlantic. 1919，Britain, radio broadcasting station 1920，Pittsburgh, America, radio broadcasting station TV: 1884,Paul Nipkow（尼普科夫 ）, German, assumption of mechanical scanning TV 1927,Baird（贝尔德 ）,picture transmission,London to a ship in Atlantic. 1923&19

16、24,Zworykin（佐里金 ）,Russian,camera tube&picture tube 1931, Zworykin, the worlds first full-electronic TV system,13,Radar（Radio Detection and Ranging） World War 2:detect fighters(airplane), the most active part of EM theory 1936，watt, British,surveillance radar, bomber英国的瓦特1938，America, controll artill

17、ery 1940，multisegment magnetron，microwave radar 1944，automaticly track airplane 1945，display technique, eliminate background interference,14,Satellite communication technology: 1958, America, communication 1964, stationary synchronous satellite,Americas& Europe&Africa, communication& TV 1965,commerc

18、ial stationary synchronous satellite 1969, satellite communication is becoming mature.,15,Global positioning satellite technology 1957, introduce radar to satellite, satellite-based position & navigation 1958, America, start to carry out this plan 1964,Transit navigation satellite system（子午仪导航卫星系统 ）, 1973, GPS plan: Navigation Satellite Timing and Ranging（导航卫星定时和测距 ）/Global Positioning System NAVSTAR（导航星（美国全球定位系