We introduce a general-purpose Sputnik and simple principles to help us further understand China's first man-made earth satellite was successfully launched, of great significance in the political, military, economic and scientific technology. Used in communications generally, people use radio waves to communicate over long distances. Through radio, telegraph, telephone, and the battle victorious Mao Ze-dong thought spread throughout the country, to the world.
The radio wave propagation is how it? We all know that when we went into a depression dropped a stone in the pond, the water immediately form a circle of Lian Yi, and stones to fall to the point spread out around the center. When the wave encounters the wall or other obstacles in advance wave was reflected back in the opposite Fangxiang Wei continued to move forward. When radio waves transmitted, like this but also as the radio waves transmitted distance. But we can wave the naked eye can see, while radio waves are invisible. Radio waves from a variety of different bands, which rely on a short wall panel natural atmosphere reflected. The screen wall is called the ionosphere, which is about 50 km to 1000 km in the atmosphere. This relies on the ionosphere, shortwave radio transmission can far. We use short-wave radio, the revolutionary people of the world can hear the broadcast Beijing, Chairman Mao's voice heard. However, the refractive power of the ionosphere will be a lot of influence, such as activities, climate, seasonal changes in the sun, and so on. Sometimes even make short-wave communication is interrupted.
如果用人造卫星作为一个通讯的中继站(转送站)，无线电波通过卫星中继站放大后，再向地球发射。这样，无线电通讯就几乎不受电离层变化的影响了。所以，我们可以通过人造卫星来转播广播、传送电话、电报。电视的电波与普通无线电波有些不同，它是一种超短波。电视的电波一直向前进，能够穿透电离层，它不像一一般的n无线电短波那样，碰到电离层后可以反射回来，传得更远，所以，电视节目播送的范围，一般只有一百公里左右。如果我们发射一种特殊的能转播电视的人造卫星，供转播电视用的人造地球卫星，它的轨道是特殊设计的。有一种通讯卫星在几万公里的高空，它的轨道平面对于地球赤道平面的交角是零度或者接近于零度，围绕地球运转一周的时间，大约24小时(严格地说应该是23小时56分)。因为它绕地球转一周的时间与地球自转一周的时间是一样的，所以，人造卫星看起来就好像在天空某一个位置固定不动。这种通讯卫星叫做“同步卫星”。
使全世界各地都可以同时看到一个地方发出的电视，单发射一颗同步卫星还是不够的。如我国地处东半球，单东半球上空有同步卫星，西半球还是看不到。如果发射几个同步卫星（列如三个），它们均匀地分布在地球上空，这样，就可以互相转播，保证全世界各地都能看到北京发出的电视。
可是，这种电视讯号比较微弱，用一般的天线是收不到的，必须使用一种大型的抛物面天线。当然，不可能也不需要每个电视机都装上这样一个庞大的天线，只要各地的电视转播台有这种天线进行接收并转播卫星上传播来的电视就行了。此外，一般的人造地球卫星，也可以利用来传送科学的资料。在人造地球卫星上，可以装上各种科学仪器，进行科学实验。而它所记录下来的资料，可以在预定的时间和地点，传送回地面站。
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