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1、Chapter Two Unit Three Shortwave Communication,New Words and Expressions,wireless wails adj. 用无线电波传送的 medium mi:dim adj. 中等的；平均的；convenience kn vi:nins n. 方便，便利； AM ei em amplitude modulation 调幅mplitju:d mdjlein implement implimnt vt. 实施，执行；使生效； layer lei n. 层，层次；放置者，计划者； atmosphere tmsfi(r) n. 大气，空
2、气；大气层； 风格，基调；气氛 verification verifi kein n. 证明；证实；核实,New Words and Expressions,ionosphere ai nsfi n. 电离层 skywave skaiweiv n.天波 groundwave randweiv n.地波 vacuum vkjm n. 真空，空白；空间；amateur mt(r) n. 业余爱好者；外行； inevitable in evitbl adj. 不可避免的； 必然发生的；,Text,Medium wave was one of wireless radio used early by
3、human, which covered broadcast GPS, telecommunication and so on.,中波是人们较早利用的无线电波段之一，主要用于广播、导航和通信等方面。,Shortwave across ocean was transmitted firstly in 1921. Instead of famous expert, the pioneer was an amateur.,1921年，人类首次实现了短波跨越海洋的传播。开创者并不是赫赫有名的专家，而是名不见经传的业余无线电爱好者。,there was an electronic particle la
4、yer in the atmosphere.,大气层中有一个带电粒子层。,This suppose could not be valued enough in this period.,这个假设在这一段时间没有得到人们足够的重视。,Radio wave transmitted by shortwave, named shortwave communication. Sky wave was transmitted by ionospheres reflection.,用短波进行的无线电通信，称为短波通信。天波传播正是靠电离层的反射进行的。,Text,In Mar. 1899, Marconi
5、made experiment successful, which wireless radio could be transmitted across the English Channel 45,000 meters wide. At that time, it was medium wave that Marconi used, which was radio signal with length between 1000 and 100 meters (frequency between 300一3000khz). Medium wave was one of wireless rad
6、io used early by human, which covered broadcast GPS, telecommunication and so on. 1899年3月，马可尼成功地进行了使无线电波越过45千米宽的英吉利海峡进行传送的实验。当时，马可尼所用的是中波，即波长为1000100米（相应频率为3003000千赫）的无线电波。中波是人们较早利用的无线电波段之一，主要用于广播、导航和通信等方面。,Shortwave across ocean was transmitted firstly in 1921. Instead of famous expert, the pioneer
7、 was an amateur. Shortwave is radio between 100一10 meters (frequency between 3一30khz). Because of long-distance transmission, cheapness and convenience, shortwave exceeded AM in the telecommunication and broadcast.,1921年，人类首次实现了短波跨越海洋的传播。开创者并不是赫赫有名的专家，而是名不见经传的业余无线电爱好者。短波是波长10010米(相应频率为330兆赫)的无线电波。由于
8、短波传播距离远、经济方便，在通信和广播领域，短波传播很快超过了中波传播。,Transmitting to 3000 kilometers, Marconi implemented transmission, radio across ocean in Dec.1901. Many scientists begin to reflect from then on, that it was impossible for telecommunication across ocean, because longer radio wave was transmitted on earth, weaker
9、 signal was, according to traditional theory. However, how could this radio wave be transmitted from Britain to Newfoundland in North America 3000 km far.,1901年12月，马可尼实现了无线电波的越洋传播，传送距离达3000千米。这促使许多科学家思考这样的问题：按照传统理论，无线电波沿地面传输时会随距离增加而急剧衰减，越洋通信是不可能实现的，这一次无线电波怎么会从英国传播到3000千米之外北美的纽芬兰呢？,In order to explai
10、n it, British electric engineer Heaviside and American thelecom engineer Kennelly supposed bravely that, Marconis radio wave could travel deviously around the planet, the reason was that, there was an electronic particle layer in the atmosphere, which could exist by sun ultraviolet playing ionizatio
11、n with air in the atmosphere.,为了解释上述现象，英国电气工程师亥维赛及美国的通信工程师肯内利(生于印度)大胆地做出猜测：马可尼的无线电信号所以能绕地球弯曲传播，可能是大气层有带电粒子层的缘故，而这个带电粒子层，是由于太阳紫外线对大气层中空气的电离作用而产生的。,In the 1919, British physicist and radar expert Walson Watt proofed indirectly on theory that, there was a conductive layer in the atmosphere in the resea
12、rch of radio waves transmission in the vertical radiation device. Because of lacking experimental verification, this suppose by Heaviside and Kennelly could not be valued enough in this period.,1919年，在研究无线电波在垂直辐射器中的传播时，英国物理学家、雷达专家沃森瓦特，从理论上间接证明了大气层上空存在一个导电的气层。由于没有经过实验验证，亥维赛及肯内利有关带电粒子层反射电磁波的假设，在这一段时间没
13、有得到人们足够的重视。,British famous physicist Appleton found in 1926 the Appleton ionosphere (F-ionosphere), who won Nobel Prize in 1947 because of this contribution. 1926年，英国著名物理学家阿普尔顿发现了阿普尔顿电离层(F电离层)。由于这一突出贡献，1947年他荣获诺贝尔物理学奖。,1930, British physicist Walson Watt named this conductive particle layer on the a
14、tmosphere as ionosphere formally. 1930年，英国物理学家沃森瓦特正式把存在于高空大气层中的带电粒子层命名为“电离层”。,Radio wave transmitted by shortwave, named shortwave communication, was transmitting through skywave and groundwave. Skywave was transmitted by ionospheres reflection. For less depletion, little power and light cost, it ca
15、n play communication and broadcast in long distance. Shortwave was a major method in the international broadcast, which was also usual wave band in the modern amateur radio telecommunication.,用短波进行的无线电通信，称为短波通信，它主要靠天波和地波两种方式传播。天波传播正是靠电离层的反射进行的，它的传播衰耗小，因此用较小的功率、较低的成本，就能进行远距离的通信和广播。短波广播至今仍是国际广播的主要手段，短
16、波波段也是现代业余无线电通信常用的波段。,The former Soviet Union built up a shortwave broadcast station with 120kilowatt in 1938, which had the biggest power in the world at that time.,1938年，前苏联建成了一个功率为120千瓦的短波无线电广播电台PB?6，它是当时世界上功率最大的一个电台。,In fact, from American chemist Lan Mauer invented vacuum electronic tube in 1912
17、, which was put into practice. And set up in 1921, Radio Corporation of America put related tubes and radio components together, which authorized by Marconi, Bell Telephone, and General Electric Corporations. So these products began to be manufactured in massive scale, and electronics became an independent industry. Not only development of radio broadcast and telecommunication industry was promoted, but also huge energy was brought into radio amateurs activities. In this way, it was inevitable for them to find shortwave.,
