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常听中波广播的同志或许已经发现,同样是傍晚前后,在夏时制听广播要比非夏时制时干扰小,音质好,这是为什么呢?我们知道,无线电波按频率高低或波长波短分为中波、短波和超短波等多种。国内中波广播的频率范围是526.5～1606.5 kHz(波长545.45～187.5 m),它主要靠“地波”和“天波”两种方式传播。地波又称表面波,指沿着地面传播的无线电波。地波在传播过程中,由于部分能量要被大地吸收,很快减弱,因而传播距离不远。但它不受气候影响。天波指受到高空(自地面大约50 km以上)电离层反射或折射后返回地面的无线电波。由于电离层的浓度和高度经常变化,天波传播没有地波稳定,但它传播距
The comrades who often listen to the radio in the waves may have noticed that the same evening before and after that, in the daylight saving time, the system had less interference with non-daylight hours and better sound quality. What is the reason for this? We know that radio waves are transmitted by frequency, Wave short divided into medium wave, short wave and ultrashort wave and other. The frequency range of domestic medium-wave broadcasting is 526.5-1606.5 kHz (wavelength 545.45-187.5 m), which mainly spreads by means of “ground wave” and “sky wave”. Ground wave, also known as surface wave, refers to the spread of radio waves along the ground. In the process of propagation of ground waves, due to some of the energy to be absorbed by the earth, soon weakened, and therefore not far from the transmission. But it is not affected by the weather. A sky wave refers to a radio wave that returns to the ground after being reflected or refracted by the ionosphere at high altitude (about 50 km above the ground). Due to the frequent changes in ionospheric concentrations and altitudes, there is no ground-wave propagation that is stable, but it propagates away from